Physics — MPSC PYQ

एकाच पदार्थाच्या दोन रॉडच्या लांबी त्रिजेचे गुणोत्तर 1 : 2 आणि 2 : 3 आहे. जर रॉडच्या दोन्ही टोकांमधील तापमानातील फरक समान असेल तर उष्णता प्रवाहाचे गुणोत्तर किती असेल ? The ratio of lengths to radii of two rods of same material is 1 : 2 and 2 : 3. If temperature difference between two ends of the rod is same, then what will be the ratio of heat flow ?

Heat flow formula Q = (KA Delta T)/L. Since material is same, K is constant. Using radii ratios and length ratios, the heat flow ratio calculates to 8 : 9.

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खालील दिलेल्या रोधकांच्या नेटवर्क (नेटवर्क ऑफ रेजिस्टेन्स) मध्ये बॅटीमधून _________ विध्यूतधारा वाहिल. In the network of resistances shown below, Current through the battery will be _________.

The resistors form a Wheatstone bridge: 2 Ω and 4 Ω on one path, 1 Ω and 2 Ω on the other, with the 3 Ω across the middle. Since 2/1 = 4/2 the bridge is balanced, so no current flows through the 3 Ω. The two paths are 2 + 4 = 6 Ω and 1 + 2 = 3 Ω in parallel, giving 6 × 3 / 9 = 2 Ω. The current from the 2 V battery is 2 / 2 = 1.0 A.

खालीलपैकी कोणती भौतिक राशी टकरीच्या दरम्यान अक्षय राहते ? Which physical quantity conserved during collision ?

According to the Law of Conservation of Momentum, the total momentum of a system of colliding objects remains constant before and after the collision (in the absence of external forces).

_____________ या प्रक्रियेत न्यूट्रीनो कण उत्सर्जित होतो. Neutrino particle is emitted in the process of _____________.

During beta decay, a neutron transforms into a proton while emitting an electron (beta particle) and an antineutrino, or a proton into a neutron emitting a positron and a neutrino.

तापमान वाढीचा परिणाम वायूच्या मितप्रवाहीपणा/स्निग्धता (viscosity) वर कसा होतो ? What is the effect of increase in temperature on viscosity of gases ?

Unlike liquids where viscosity decreases with temperature, the viscosity of gases increases with an increase in temperature because higher temperature increases molecular collision rates and momentum transfer.

लेझर व अणू किंवा रेणू यांचा काय संबंध आहे ? What is the relation between laser and atoms or molecules ?

LASER stands for Light Amplification by Stimulated Emission of Radiation, indicating it works on the principle of stimulated emission.

लेझर किरण कशासाठी वापरला जात नाही ? Laser beam is not used for which of the followings ?

Laser beams are highly directional, coherent, and monochromatic, making them unsuitable for certain diffuse lighting applications like general room illumination.

लेझर हा सामान्य प्रकाश स्रोतापेक्षा वेगळा आहे कारण _________ Laser is different than the common light sources because _________

Laser light is different from ordinary light because it is coherent, monochromatic (single wavelength), and highly directional.

लेझर किरणसाठी कोणाला नोबेल पुरस्कार मिळाला आहे ? Who got noble prize for Laser ?

Charles Townes, Nikolai Basov, and Alexander Prokhorov received the Nobel Prize in Physics in 1964 for fundamental work in quantum electronics leading to the laser-maser principle.

पहिला गॅस लेझर कोणी विकसित केला ? Who developed first gas Laser ?

Ali Javan, along with William R. Bennett and Donald Herriott, developed the first gas laser (Helium-Neon laser) in 1960 at Bell Labs.

वर फेकलेल्या कणाची गती शून्य असते परंतु त्याचे त्वरण किती असते ? / A particle thrown up has zero velocity but how much will be the acceleration ?

At the highest point of its trajectory, a particle thrown upwards has zero instantaneous velocity, but the acceleration acting on it is still the constant acceleration due to gravity (g downwards).

खालीलपैकी कोठे बर्नोली समीकरणाचा उपयोग नाही ? / Which one of the following is not an application of Bernoulli equation ?

Bernoulli's equation is based on conservation of energy for fluid flow, applied in various engineering and natural phenomena. Options not based on this principle are treated as correct answers for 'not an application'.

खालीलतील तापमानावर (300 के) वस्तुद्वारे उत्सर्जित होणाऱ्या औषणीय प्रारणासाठी महत्वपूर्ण योगदान तरंगलांबी किती असते ? / At room temperature (300k), what is the significant contribution wavelength for the thermal radiation emitted by a body ?

According to Wien's displacement law, for a body at room temperature (300 K), the peak wavelength of emitted thermal radiation lies in the infrared region around 9550 nanometers.

खालीलपैकी कोणते वाक्य चुकीचे आहे ? / Which of the following sentence is wrong ?

Neutrons are neutral subatomic particles with no electrical charge, so statement (IV) claiming neutrons have a positive charge is factually incorrect.

खालील विधने सत्य की असत्य ते लिहा. (I) आवाजाच्या प्रसारासाठी माध्यमाची गरज असते. (II) आवाजाच्या वारंवारतेचे हर्ट्झ हे एकक आहे. (III) आवाजाची तीव्रता मोजण्यासाठी डेसिबल हे एकक आहे. Say whether following sentences are true or false : (I) For propagation of sound medium is necessary. (II) Unit of frequency of sound is Hertz. (III) Loudness of sound is expressed in decibel unit.

All given statements are correct: Sound requires a material medium for propagation, frequency is measured in Hertz (Hz), and loudness/intensity is measured in decibels (dB).

खालीलपैकी कोणती तरंगलांबी पदार्थाच्या स्फटिक आंतररचना अभ्यासण्यासाठी वापरतात ? (1) अतिनील तरंगलांबी (2) गॅमा तरंगलांबी (3) क्ष-किरण तरंगलांबी (4) अवरक्त तरंगलांबी Which of the following wavelengths are used to study the crystal structure of material ? (1) Ultraviolet wavelength (2) Gamma Rays wavelength (3) X-Rays wavelength (4) Infrared wavelength

X-rays have wavelengths comparable to the interatomic spacing in crystals (about 1 angstrom), making them ideal for studying crystal structures via diffraction.

_______ ह्या पदार्थाचा प्रतिरोधकता निर्णायक (critical) तापमानाच्या खाली शून्य होते. _______ are materials whose resistivities become zero below a critical temperature.

Superconductors are materials that exhibit zero electrical resistance when cooled below a specific critical temperature.

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मोटरमध्ये माघारी विद्युतगामकाचे महत्व काय आहे ? Why is back emf important in a motor ?

Back emf in a DC motor opposes the supplied voltage, regulates the current drawn, and helps control the speed of the motor automatically.

जर एखादी वस्तू 36° अंशात तिरप्या असणाऱ्या दोन समतल आरशांमध्ये समरूप ठेवली, तर किती प्रतिमा तयार होतील ? If an object is placed symmetrically between two plane mirrors inclined at an angle of 36°, then how many images will be formed ?

The number of images formed by two plane mirrors inclined at an angle theta is given by (360/theta) - 1 if 360/theta is even. Here 360/36 = 10 (even), so 10 - 1 = 9.

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मोटर चालू केल्यावर विद्युतप्रवाह सुरुवातीला खूप मोठा का असतो ? Why is the current initially very large when a motor is turned on ?

When a motor is just turned on, its speed is zero, so back emf is zero. Due to the absence of back emf opposing the supply voltage, a large current initially flows through the armature.

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जेव्हा मोटारीतील यांत्रिक भार वाढतो, तेव्हा माघारी विद्युतगामकाचे काय होते ? What happens to the back emf, when the mechanical load on the motor increases ?

When mechanical load on a DC motor increases, the speed decreases, which in turn decreases the back emf (Eb) as Eb is directly proportional to speed.

जेव्हा α-कण किरणोत्सारी घटकातून बाहेर पडतात तेव्हा When α-particle emits from a radioactive element then

An alpha particle is a helium nucleus (He-4,2). When emitted from a radioactive nucleus, the mass number decreases by 4 and the atomic number decreases by 2.

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चालू मोटरवर अतिरिक्त भार टाकल्यास काय होईल ? What can happen if a heavy load is given on a running motor ?

When a heavy load is applied to a running motor, it draws more current, leading to overheating and potential burnout due to excessive electrical stress.

मुलाचा ताप 104°F आहे. हे तापमान किती डिग्री सेल्सिअस आहे ? The fever of a child is 104°F. What is this temperature in degree Celsius ?

Using the conversion formula C/5 = (F - 32)/9, for 104°F: (104 - 32)/9 = 72/9 = 8; then C = 8 * 5 = 40°C.

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दोन वस्तूंचे वस्तुमान अनुक्रमे 200 gm आणि 300 gm असून ते एकाच रेघेवर व एकाच दिशेने 8 m/s आणि 4 m/s वेगाने जात आहेत. त्यांची टक्कर होते व टक्कर झाल्यावर पहिली वस्तू 5 m/s वेगाने गतिमान होते. टक्कर झाल्यावर दुसऱ्या वस्तूचा वेग काढा : Two objects having masses 200 gm and 300 gm, are moving along the same line in the same direction with velocities 8 m/s and 4 m/s, respectively. After the collision of the two objects, the first object moves with a velocity of 5 m/s. After collision, the velocity of the other object is :

Using the Law of Conservation of Momentum: m1u1 + m2u2 = m1v1 + m2v2. Substituting the values gives the final velocity of the second object as 6 m/s.

दोन वस्तूंची परस्पर क्रिया होत असताना त्यांच्यावर जर काही बाह्य बल कार्यरत नसेल, तर त्याचा एकूण संवेग, The two objects are interacting without external force, their total momentum

According to the Law of Conservation of Momentum, if no external force acts on a system of interacting objects, their total momentum remains constant (conserved).

एका बंदुकीचे वस्तुमान 6 kg असून त्यातून गोळी झाडल्यानंतर बंदूक 170 cm/s वेगाने प्रतिकेक्षिपत होते, तर बंदुकीचा संवेग काढो : The mass of a gun is 6 kg and it recoils with a speed 170 cm/s. What is the momentum of the gun ?

Momentum = mass × velocity. Mass of gun = 6 kg, recoil velocity = 170 cm/s = 1.7 m/s. Momentum = 6 × 1.7 = 10.2 kg m/s or in cgs units 6000 g × 170 cm/s = 1020000 g cm/s.

दोन वस्तू, A आणि B यांचे वस्तुमान अनुक्रमे m1 आणि m2 आहे. न्यूटनच्या गतीविषयक तिसऱ्या नियमानुसार, A वस्तू B वस्तूवर जे बल प्रयुक्त करते ते, Two objects, A and B have masses m1 and m2, respectively. According to Newton's third law of motion, the force exerted by A on B is :

Newton's third law states that to every action, there is an equal and opposite reaction. Thus, the force exerted by A on B is equal in magnitude and opposite in direction.

संवेग परिवर्तनाचा दर, The rate of change of momentum is :

According to Newton's second law of motion, the rate of change of momentum of an object is directly proportional to the applied unbalanced force.

110 ओहम रोध असलेल्या उपकरणाच्या दोन टोकांमध्ये 33 V विभवांतर प्रयुक्त केले असता उपकरणातून काही विद्युतधारा वाहते. 500 ओहम रोध असणाऱ्या उपकरणातून तेवढीच विद्युत धारा वाहू देण्यासाठी त्याच्या दोन टोकांमध्ये किती विभवांतर प्रयुक्त करावे लागेल? When a potential difference of 33 V is applied to a device whose resistance is 110 $\Omega$, some current flows through it. If the same current is to be passed through a device whose resistance is 500 $\Omega$, then how much potential difference is to be applied?

According to Ohm's law, current remains constant. First find current I = V1 / R1 = 33 / 110 = 0.3 A. Then find new voltage V2 = I * R2 = 0.3 * 500 = 150 V.

खालीलपैकी नैसर्गिक चुंबकाचे नांव कोणते आहे? Which one of the following is a natural magnet?

Magnetite (Fe₃O₄) is a naturally occurring mineral that possesses magnetic properties, making it a natural magnet.

सोनार (साऊंड नेव्हीगेशन श्रेणी) तंत्र ______ यासाठी वापरले जाते. SONAR (Sound Navigational Ranging) technique is used for ______ .

SONAR uses ultrasonic sound waves to navigate, measure distances, and detect objects underwater, such as submarines or sea beds.

एका ध्वनी तरंगाची वारंवारता 1000 हर्ट्झ असून तरंगलांबी 0.25 मीटर आहे. जर तो एका विशिष्ट माध्यमातून 5 सेकंद प्रवास करत असेल, तर कापलेले अंतर काढा. Calculate the distance travelled by a sound wave having frequency 1000 Hz and wavelength 0.25 m, if it travels for 5 seconds in a certain medium.

Speed of sound v = frequency * wavelength = 1000 Hz * 0.25 m = 250 m/s. Distance = speed * time = 250 m/s * 5 s = 1250 meters.

दोन समतल आरशामध्ये एक मांजर बसली आहे, जर दोन समतल आरशामधील कोन 30 अंश असल्यास, मांजरीच्या किती प्रतिमा दिसतील ? A cat is sitting in between two plane mirrors. If the angle between two plane mirrors is 30 degrees, how many images of the cat will appear?

Number of images formed by two inclined mirrors is given by formula (360/theta). Here 360/30 = 12. Since 12 is even, the number of images is (12 - 1) = 11.

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प्रकाशाच्या वर्ण पटामध्ये कोणत्या प्रकाशाचा समावेश असतो ? Optical spectrum consist of ____________.

The optical spectrum (visible spectrum) consists of all the electromagnetic wavelengths that are visible to the human eye, commonly known as VIBGYOR.

प्रकाशाचा वेग ____________ असतो. Speed of light is ____________.

The speed of light in a vacuum is a fundamental physical constant, approximately equal to 3 × 10⁸ meters per second.

प्रकाशाचे एकक सहसा ____________ मध्ये दिले जाते. Light unit is generally expressed in ____________.

Light is commonly measured in lumens or candela for luminous flux and intensity, but generally standard scientific units or decibel/lux are referenced based on context.

प्रकाश तरंग मुख्यत: ____________ स्वरूपात असतात. Light is generally in the form of :

Light travels in the form of electromagnetic waves, specifically transverse waves.

अवरक्त प्रकाश किरणांची वारंवारिता ही जांभळ्या रंगाच्या प्रकाश किरणे पेक्षा ____________. Frequency of infrared light is ____________ than violet light.

Infrared light has longer wavelengths and lower frequency compared to violet light, which has the highest frequency in the visible spectrum.

जर पाण्याची घनता 1000 kgm⁻³ आणि तांब्याची घनता 8.9 × 10³ kgm⁻³ असेल तर तांब्याची सापेक्ष घनता किती ? If density of water is 1000 kgm⁻³ and density of copper is 8.9 × 10³ kgm⁻³. What is relative density of copper ?

Relative density is the ratio of the density of a substance to the density of water. Since it's a ratio of identical units, it is a dimensionless quantity, making 8.9 the correct answer.

जर प्रकाश पहिल्या माध्यमातून 2 × 10⁸ ms⁻¹ वेगाने जाताना दुसऱ्या माध्यमात त्याचा वेग 1.25 × 10⁸ ms⁻¹ होत असेल तर दुसऱ्या माध्यमाचा पहिल्या माध्यमाच्या संदर्भातील अपवर्तनांक काढा. Find the refractive index of the second medium with respect to the first medium, if light moves through the first medium with velocity 2 × 10⁸ ms⁻¹, which changes to 1.25 × 10⁸ ms⁻¹ in the second medium.

Refractive index of second medium with respect to first medium is given by the ratio of speed of light in the first medium to that in the second medium: (2 × 10⁸) / (1.25 × 10⁸) = 1.6.

एका माणसाला 25 किलो वजनाची बॅग 5 मीटर उंचीवर नेण्यास 30 सेकंद लागतात, तर त्या माणसाने वापरलेली शक्ती किती ? A person carrying a bag of total mass 25 kg climbs upto a height 5 meters in 30 seconds. How much power the man needs to carry the bag ?

Power is work done per unit time. Work done = mgh = 25 * 9.8 (or 10) * 5. Power = Work / Time. Calculating gives approximately 40.8 W depending on g value.

लेसर किरण पृथ्वीवरून चंद्रकड सोडूननंतर चंद्राच्या पृष्ठभागापासून परावर्तित होऊन पृथ्वीवर परत येण्यास 2.56 सेकंद लागतात. तर चंद्राच्या पृथ्वीभोवतीच्या परिभ्रमण कक्षेची त्रिज्या किती ? A laser light beamed at the Moon takes 2.56 s to return to earth after reflection at the Moon's surface. How much is the radius of the lunar orbit around the Earth ?

Time taken for round trip is 2.56 s, so time to reach the moon (t) = 2.56 / 2 = 1.28 s. Distance (Radius) = Speed of light * time = (3 × 10⁸) × 1.28 = 3.84 × 10⁸ m.

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पृथ्वीच्या केंद्रापासून R या अंतरावर एक उपग्रह गोलकार कक्षेत फिरत आहे. उपग्रह ϕ या कोनातून फिरताना व्यापले जाणारे क्षेत्र A = R²ϕ/2 आहे. केप्लरच्या दुसऱ्या नियमानुसार असे सूचित होते की, उपग्रहाला 2ϕ कोनाितका जाण्यासाठी लागणारा वेळ : Consider a satellite in circular orbit around the Earth at a distance R from the Earth's center. The area that the satellite sweeps out as it moves through an angle ϕ is given by A = R²ϕ/2. Kepler's second law implies that the time that it takes to move through 2ϕ is :

According to Kepler's second law, the areal velocity is constant, meaning equal areas are swept out in equal intervals of time. Since area A is proportional to angle phi (A = R²*phi/2), sweeping through an angle of 2phi takes double the time required to sweep through phi.

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पृथ्वीच्या केंद्रापासून R इतक्या अंतरावर m इतक्या वस्तुमानाचा एका अग्निबाणाला गतिमान होण्यासाठी लागणारी ऊर्जा E = GmM_e (1/R_e - 1/R) इतकी आहे. तर ह्या अग्निबाणाला पृथ्वीच्या गुरुत्वाकर्षण क्षेत्रापासून पूर्णतः निसटण्यासाठी कमीत कमी किती वेग दिला पाहिजे ? The amount of energy needed to move a rocket having mass m from the surface of the Earth to a distance R from the Earth's center is E = GmM_e (1/R_e - 1/R). What is the minimum velocity, the rocket must have in order to completely escape the Earth's gravitational field ?

The escape velocity from the Earth's gravitational field is derived by setting the total mechanical energy to zero, yielding v = sqrt(2GMe / Re).

जेव्हा एखाद्या ध्वनी तरंगाचे संपीड़न दृढ भंतीवर आदळेल तेव्हा त्याचे प्रतिबिंबित रूप हे : When a compression of sound waves is incident on rigid wall, it is reflected as :

At a rigid boundary, particle displacement has a node and pressure has an antinode -- the opposite of what happens at a free/open boundary. This means a pressure compression reflects back as a compression (not a rarefaction), with no phase change in the pressure wave. (The displacement wave does invert by 180 degrees, but the question is about the compression/pressure wave itself.)

थॉम्प्सनच्या अणू प्रतिकृतीवरून खालीलपैकी कोणते गुणधर्म स्पष्टपणे समजतारा ? / Which of the following properties of atom could be explained correctly by Thompson Model of atom ?

Thomson's model of the atom (plum pudding model) could successfully explain the overall electrical neutrality of the atom, showing how positive and negative charges balance each other.

ट्रिटियमचे अर्धआयुष्य 12.5 वर्षे असून त्याचा बीटा किरणांनी क्षय होतोय. 25 वर्षानंतर मूळ ट्रिटियमचा किती अंश अक्षय शिल्लक राहील ? / Tritium has a half-life of 12.5 years, undergoing beta decay. What fraction of original Tritium will remain undecayed after 25 years ?

The half-life of tritium is 12.5 years. After 25 years, which is 2 half-lives (25 / 12.5 = 2), the remaining undecayed fraction is (1/2)² = 1/4 of the original amount.

300 वॅंचे एक धुलाई मशीन प्रतिदिन 1 तास चालवले जाते. जर एका युनिटचा दर ₹ 3.00 असेल, तर मार्च महिन्यामध्ये त्या मशिनसाठी वापरलेल्या विजेचा खर्च किती ? / A washing machine rated 300 Watt is operated for one hour/day. If the cost of one unit is ₹ 3.00, what will be the cost of the energy to operate a washing machine for the month of March ?

Power = 300 W = 0.3 kW. Energy consumed per day = 0.3 kW × 1 hour = 0.3 kWh (units). For March (31 days), total units = 31 × 0.3 = 9.3 units. Cost = 9.3 × Rs. 3.00 = Rs. 27.90.

उपग्रहमध्ये, अंतराळवीर हा वजनरहित अवस्था अनुभवतो कारण ______

Inside an orbiting satellite, an astronaut experiences weightlessness because both the satellite and the astronaut are in free fall towards the Earth under gravity, making the normal reaction force from the floor zero, leading to option 4 (none of the above statements are correct in the way standard physics options are framed here as 'फक्त ड').

इलेक्ट्रॉनिक दळणवळण पद्धतीमध्ये (डिजिटल) अंकात्मक संदेश

In digital communication, numerical messages are presented in discrete steps, use binary number systems (0 and 1), and do not provide continuous message streams like analog signals.

प्रकाशाकीय तंतू हा खालीलपैकी कोणत्या तत्त्वावर आधारित आहे ? Optical fibre is based on which of the following principles ?

Optical fibres work on the fundamental principle of Total Internal Reflection (TIR), where light rays traveling through the core undergo repeated total internal reflections.

दोन वस्तूंच्या अप्रत्यास्थ धडकेच्या दरम्यान खालीलपैकी कोणत्या बाबींचे संवर्धन होईल ? During inelastic collision between two bodies, which of the following quantities always remains conserved ?

During any type of collision (elastic or inelastic), total linear momentum of the system is always conserved according to Newton's laws and the law of conservation of momentum.

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कोष्टकात दिल्याप्रमाणे घनता असणाऱ्या सोन्यापासून आणि तांब्यापासून जर 0.50 kg. च्या समान वजनाचे दोन गोळे (चेंडू) बनवले तर / According to densities given in the table, if we prepare two spheres out of Gold and Copper each of a similar weight of 0.50 kg., then (सारणीतील घनता / Densities from the table: सोने / Gold = 19.30 g/cm³, तांबे / Copper = 8.96 g/cm³.)

Density equals mass divided by volume (Density = Mass / Volume). Since gold has a much higher density than copper, for the same mass (0.50 kg), gold will occupy less volume, meaning the golden sphere is smaller.

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एका वस्तूची उंची 3 सेमी असून 24 सेमी वक्रता त्रिज्या असणाऱ्या अंतर्वक्र आरशापासून 20 सेमी अंतरावर ठेवली आहे. सुस्पष्ट प्रतिमा मिळवण्यासाठी आरशापासून पडदा किती अंतरावर असावा ? तसेच प्रतिमेचा आकार किती ? / An object 3 cm in size is placed 20 cm in front of a concave mirror of radius of curvature 24 cm. At what distance from the mirror should a screen be placed in order to obtain a sharp image ? Also, what is the size of the image ?

Using mirror formula 1/f = 1/v + 1/u with R=24 cm (f=-12 cm) and u=-20 cm, we find v=-30 cm. Magnification gives the image size as -4.5 cm.

सुस्पष्ट दृष्टीचे लघुत्तम अंतर 50 सेमी असणाऱ्या व्यक्तीच्या चष्म्याची नाभीय शक्ती किती असावी ? / What focal power should the reading spectacles have for a person for whom the least distance of distinct vision is 50 cm ?

Power of lens is given by P = 1/f (in meters). For distinct vision correction, focal length calculation gives the required power in dioptres.

यादीतील खालील उपकरणांमध्ये आरे व भिंग वापरले जातात. त्यानुसार त्यांचे वर्गीकरण करा. (i) हेडलाइट्स (ii) दूरदर्शी (iii) संयुक्त सूक्ष्मदर्शी (iv) प्रोजेक्शन लॅम्प (v) फ्लडलाइट्स (vi) साधा सूक्ष्मदर्शी In the list of the following instruments, mirrors and lenses are used. Classify them accordingly. (i) Headlights (ii) Telescopes (iii) Compound microscopes (iv) Projection lamps (v) Floodlights (vi) Simple microscopes

Headlights, projection lamps, and floodlights use mirrors (concave/parabolic) to reflect and direct light, whereas telescopes, compound microscopes, and simple microscopes use lenses for refraction and magnification.

1 मिमी × 1 मिमी च्या चौरसाची नक्षी असलेले कार्ड शीट, डोळ्यांच्या अगदी जवळ असलेल्या 9 सेमी नाभीय अंतराच्या बहिर्वर्क भिंगातून 9 सेमी अंतरावरून बघितल्यास, त्या कार्ड शीट वरील चौरस ________ आकाराचे दिसतील. A card sheet divided into squares, each of size 1 mm × 1 mm is being viewed at a distance of 9 cm through a convex lens of focal length 9 cm held close to the eye. The squares on the card sheet will be observed to be of size

When object distance equals focal length of a convex lens, the image is formed at infinity, making the calculation straightforward based on magnification formulas.

फ्रेसनल्स बायाप्रिझम मध्ये (λ) तरंगलांबीची किंमत कशावर अवलंबून असते ? / In Fresnel's Biprism, the value of wavelength (λ) depends upon

In Fresnel's biprism experiment, the wavelength of light depends on fringe width, distance between coherent sources, and distance between slit and eyepiece, as all these variables are mathematically related in the fringe width formula.

ज्या व्यक्तीचे सुस्पष्ट दृष्टीचे लघुत्तम अंतर 50 cm आहे, अशा व्यक्तीच्या चष्माच्या भिंगांचे नाभीय अंतर किती असेल ? / What focal length should the spectacles have for a person for whom the least distance of distinct vision is 50 cm ?

For a person with least distance of distinct vision D = 50 cm (normal is 25 cm), a convex lens is used to correct hypermetropia. Using the lens formula with object distance u = -25 cm and image distance v = -50 cm gives a focal length of 50 cm.

10 ओमचा रोध 12 V च्या विद्युतघटस जोडल्यास रोधातून 1.1 A विद्युतधारा वाहते. विद्युतघटाचा अंतर्गत रोध काढा. A resistor of 10 Ω connected across a cell of emf 12 V, draws the current of 1.1 A. Find the internal resistance of the cell.

Using formula E = I(R + r), where E = 12V, I = 1.1A, R = 10Ω. 12 = 1.1(10 + r) => 10 + r = 12/1.1 = 10.91 => r = 0.91 Ω.

एकमेकांपासून 1 मिलिमीटर अंतरावर असलेली दोन समांतर रेखाच्छिद्र पडद्यापासून 1 मीटर अंतरावर ठेवलेल्या आहेत. त्यांच्यावर 500 नॅनोमीटर तरंगलांबीची शलाका सोडल्यानंतर पडद्यावर व्यतिकरण परिणामामुळे तयार झालेल्या पत्तीमधील अंतर किती ? Two parallel slits 1 millimetre apart are placed 1 metre away from the screen. What is the fringe separation due to interference effect, when a beam of wavelength 500 nanometres is incident on them ?

Fringe separation formula β = λD / d. Substituting λ = 500 nm, D = 1 m, d = 1 mm gives the fringe width as 0.5 mm.

एका वाफेच्या इंजिनला 3.6 × 10⁹ J/min दराने उष्णता पुरवली जाते. त्यापासून इंजिन 5.4 × 10⁸ J/min दराने कार्य करते. अशा इंजिनची कार्यक्षमता किती टक्के असेल ? A steam engine delivers 5.4 × 10⁸ J of work per minute by taking 3.6 × 10⁹ J of heat from its source. What is the efficiency of the engine ?

Efficiency = (Work output / Heat input) * 100 = (5.4 × 10⁸ / 3.6 × 10⁹) * 100 = (0.15) * 100 = 15%.

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श्रव्यातीत तरंग असे तरंग आहेत की ते Ultrasonic waves are those waves which

Ultrasonic waves have frequencies above the human hearing range (greater than 20 kHz), hence they cannot be heard by human beings.

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हृदयांच्या ठोकळ्यांचे तंत्रज्ञान यावर आधारित आहे The echocardiography technique is based on

Echocardiography uses high-frequency sound waves (ultrasonic waves) to produce live images of the heart's structure and functions.

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समुद्राची खोली काढण्यासाठी या तंत्राचा वापर करतात : To determine the depth of sea this technique is used :

SONAR (Sound Navigation and Ranging) uses ultrasonic waves to measure distances and determine the depth of the sea by timing the echo return.

पृथ्वीवरील एका विशिष्ट ठिकाणी चुंबकीय शिखराचा आडवा घटक 0.26 एकक असून तेथील उतार कोन 60° आहे. या ठिकाणी पृथ्वीचे चुंबकीय क्षेत्र किती एकक असेल? In the magnetic meridian of a certain place, the horizontal component of the Earth's magnetic field is 0.26 units and the angle of dip is 60°. What is the magnetic field of the Earth at this location?

Using relation B = Bh / cos(theta), where Bh = 0.26 and theta = 60 degrees, total magnetic field B = 0.26 / cos(60) = 0.26 / 0.5 = 0.52 units.

ज्याच्या प्रत्येक पृष्ठभागाची वक्रता त्रिज्या 50 सेमी आहे, अशा डबल बहिर्वक्र भिंगाचे नाभीय अंतर किती असेल, जर काचेचा वकीभवन दर्शक 1.50 असेल ? What is the focal length of a double convex lens for which the radius of curvature of each surface is 50 cm and the refractive index of glass is 1.50 ?

Using the lens maker's formula 1/f = (n - 1)(1/R1 - 1/R2), with n = 1.50 and R1 = 50 cm, R2 = -50 cm, the focal length calculates to 50 cm.

लांबीचे नवीन एकक असे निवडले की ज्यानुसार निर्वात पोकळीत प्रकाशाची गती 1 एकक येते. जर सूर्यप्रकाश, सूर्यापासून पृथ्वीपर्यंतचे अंतर 8 मिनिट व 20 सेकंदात कापत असेल, तर लांबीच्या नवीन एककानुसार सूर्य व पृथ्वीमधील अंतर किती ? A new unit of length is chosen such that the speed of light in vacuum is unity. What is the distance between the Sun and the Earth in terms of the new unit, if light takes 8 minutes and 20 seconds to cover this distance ?

Time = 8 min 20 sec = 500 seconds. Since speed of light is 1 unit in the new system, distance = speed × time = 1 × 500 = 500 units.

विशेष वारंवारता असणारा एका ध्वनी तरंगाचा वेग 336 मी./से. असून तरंग लांबी 3 सेमी आहे. तर वारंवारता काढा. ती श्रवणीय असेल का ? A sound wave having certain frequency travels with a speed of 336 m/s and wavelength 3 cm. What will its frequency be ? Will it be audible ?

Using formula v = f * λ, frequency f = v / λ = 336 / 0.03 = 11200 Hz = 11.2 kHz. Since human audible range is 20 Hz to 20,000 Hz, 11200 Hz is audible.

जर दोन रोध एकसर जोडणीने जोडले, तर त्यांचा परिणामी रोध 45 Ω होतो आणि जर तेच रोध समांतर जोडणीने जोडले, तर त्यांचा परिणामी रोध 10 Ω होतो. तर त्या रोधांच्या किमती काढा. If two resistors are connected in series, the total resistance is 45 Ω and if the same resistors are connected in parallel, the total resistance becomes 10 Ω. Find the value of the individual resistors.

Using series formula R1 + R2 = 45 and parallel formula (R1 * R2) / (R1 + R2) = 10, solving quadratic equations yields individual resistors of 30 Ω and 15 Ω.

उपसर्ग गुणक 10¹⁸ चा किती ? / The prefix for the multiple 10¹⁸ is

In SI units, the prefix for the multiplier 10¹⁸ is 'exa', represented by the symbol 'E'.

एक वस्तू निर्वात पोकळीतून गुरुत्वाकर्षण क्रिये अंतर्गत मुक्तपणे खाली पडत आहे. अश्या प्रकारच्या क्रियेमध्ये खालीलपैकी कोणत्या बाबी स्थिर राहतील ? A body is falling freely under the action of gravity alone in vacuum. Which of the following quantities remains constant during the fall ?

When a body falls freely under gravity in a vacuum, mechanical energy (sum of kinetic and potential energy) remains conserved and constant due to the absence of dissipative forces like air resistance.

पुढील दोन विधानांपैकी कोणते योग्य आहे ? अ. अतिनील किरणे किरकोळ गाठींवर उपयुक्त ठरतात. ब. अवरक्त किरणे रासायनिक द्रव्यांचे पृथक्करण करतात. Which one of the following two statements is correct ? a. Ultraviolet rays help in diagnosis of small tumours. b. Infrared rays help in analysis of chemical compounds.

Ultraviolet rays are not used for diagnosing small tumours (X-rays, gamma rays or MRI are used), and infrared rays are used for studying molecular structure and thermal imaging rather than general chemical compound separation.

खालील विधानांचा विचार करा : वरीलपैकी कोणते विधान सत्य आहेत ? Consider following statements : Which of the above statements are true ?

On a misty night, sound waves refract due to temperature gradients making distant sounds clearer, and the velocity of sound increases directly with air humidity.

विद्युतचुंबकीय लहरींची पुढीलपैकी कोणती उदाहरणे आहेत ? / Which of the following are examples of electromagnetic waves ?

Television waves, ultraviolet rays, X-rays, and sunlight (visible and invisible spectrum) are all forms of electromagnetic waves differing only in frequency and wavelength.

अभ्रक कपड्यांच्या स्त्रीतीत वापरला जातो. यासंदर्भात पुढील दोन विधानांपैकी कोणते योग्य आहे ? / Mica is used in the iron for pressing clothes. In this connection, which of the following two statements is/are correct ?

Mica is an excellent electrical insulator (prevents current leakage) while being a good thermal conductor (transfers heat efficiently to the iron base).

डबक्यातील गुळगुळीत वाटोळ्‍या दगडाचे आपण जर निरीक्षण केल्यास तो आपल्याला / If we observe a pebble in a pool, the pebble would appear to be

Due to refraction of light, an object submerged in water appears raised, meaning it appears nearer to the surface than it actually is.

अतिनील किरणे _________ मधून आरपार जाऊ शकत नाहीत.

Ordinary glass absorbs ultraviolet (UV) rays and does not allow them to pass through. Quartz, fluorite, and rock salt are transparent to UV rays.

दुर्बिनीसारख्या प्रकाशीय उपकरणातील क्षेत्रभिंग व नेत्रभिंग यांच्या जोडणीतून काय आकारते ?

In optical instruments like telescopes, the combination of an objective lens (क्षेत्रभिंग) and an eye-piece (नेत्रभिंग) forms a compound eyepiece or specific optical system configuration.

पृथ्वीभोवती वर्तुळाकार कक्षेत फिरणाऱ्या उपग्रहा $E_k$ इतकी गतिज ऊर्जा आहे. पृथ्वीच्या क्षेत्रातून बाहेर निसरण्यासाठी किमान केवढी ऊर्जा दिली पाहिजे? A satellite having circular orbit around the earth has a kinetic energy $E_k$. What is the minimum amount of energy to be added so that it escapes from the earth ?

Total energy of a satellite in a circular orbit is negative and equals -Ek. To escape to infinity, total energy must become zero, requiring an additional energy equal to its kinetic energy Ek.

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त्रिस्तरीय लेझर मध्ये, अंशस्थिर अवस्था ______ मध्ये स्थिर असते. / In a three level laser, the metastable state is situated :

In a three-level laser system, the metastable state is located between the upper excited state and the lower ground state.

पंपण प्रक्रीयेचे कमीत कमी प्रमाण ______ मध्ये आवश्यक असते : / Lesser amount of pumping is required in :

A four-level laser requires a lesser amount of pumping compared to a three-level laser because the lower laser level is above the ground state, emptying rapidly.

चतुःस्तरीय लेझर दरम्यानच्या प्रक्रियेमध्ये, अंशस्थिर स्थितीचे परिवहन ______ संपुष्टात येते. / During lasing action of a four level laser transition from metastable state ends at :

In a four-level laser, the transition from the metastable state during lasing action ends at an intermediate state located just above the ground state.

प्रेरित उत्सर्जन प्रक्रियेसाठी त्रिस्तरीय लेझर मध्ये ______ . / For induced emission in a three level laser :

In a three-level laser system, population inversion requires more than 50% of the atoms to be pumped into the metastable state so that stimulated emission can dominate over absorption.

त्रिस्तरीय लेझर पद्धतीतील समष्टी व्यस्ततेत ____________ . During population inversion in three state laser :

Population inversion is a state where a higher energy state (metastable state) contains more atoms than a lower energy state, which is essential for laser operation.

रेडिओ तरंगाचा वेग हा ________ असतो. The velocity of radio waves is ________

Radio waves are electromagnetic waves. All electromagnetic waves travel through a vacuum at the speed of light (approximately 3 × 10⁸ m/s).

'रमन परिणाम' कशास म्हणतात ? / Raman effect is due to :

Raman effect is the inelastic scattering of a photon by molecules, causing a change in wavelength of the scattered light.

जर एखादी जड वस्तु क्षितिज समांतर दिशेने गुळगुळीत पृष्ठभागावरून ओढली, तर त्या वस्तुवर क्रिया करणारे बल खालीलप्रमाणे असेल. / If a heavy load is pulled along a smooth horizontal surface, then the force acting on the load may be :

When a heavy load is pulled horizontally on a smooth surface, all four forces act on it: applied horizontal force, vertical downward gravitational force, opposing frictional force, and upward normal reaction force.

खालीलपैकी योग्य वाक्यांची निवड करा. / Choose correct statements from the following :

Sound waves travel fastest in solids (a), are longitudinal waves (c), and travel slower in gases than in liquids (d). Statement (b) is false because sound cannot travel through a vacuum at all.

खालील वाक्ये विचारात घ्या. वरीलपैकी कोणती वाक्ये बरोबर आहेत ?

Blotting paper action, kerosene lamp functioning, and water transport in tall trees all rely on capillary action (surface tension/capillarity). If surface tension or related capillary properties were absent or hindered, blotting paper wouldn't absorb, kerosene lamps wouldn't draw oil, and trees couldn't transport water upwards against gravity.

खालील वाक्ये लक्षात घ्या. (a) कणाची वेधनशक्ती (सामर्थ्य) ही त्याच्या वस्तुमानाच्या व्यस्त प्रमाणात असते. (b) अल्फा कणाची वेधनशक्ती (सामर्थ्य) ही बीटा कण्याच्या वेधन शक्ती (सामर्थ्य) पेक्षा कमी आहे. खालीलपैकी कोणते विधान वरील वाक्यांची परिस्थिती योग्य रीत्या दाखवते? Consider the following statements : (a) Penetrating power of a particle is inversely proportional to its mass. (b) Penetrating power of α(alpha) particle is less than that of β(Beta) particle. Which one of the following gives a correct picture about the above statements ?

Penetrating power is inversely proportional to mass (heavier particles interact more and lose energy faster). Since alpha particles are much heavier than beta particles, their penetrating power is less than that of beta particles.

पाण्याच्या थेंबाविषयी पुढे सर्वसाधारण विधाने आहेत : (a) पाण्याच्या थेंबाचा आकार गोलाकार असण्यास पृष्ठताण कारणीभूत आहे. (b) गुरुत्वाकर्षण नसतानाही पाण्याच्या थेंबाचा आकार गोल असतो. (c) जर पाण्याचे वस्तुमान ताणले गेले तर थेंब तयार होतात. वरीलपैकी कोणते/कोणती विधान/विधाने बरोबर आहे/आहेत ?

Surface tension minimizes the surface area of a liquid, giving water drops a spherical shape. This holds true even without gravity, and stretching liquid masses results in droplet formation.