## Archive for the ‘IIT Physics’ Category

## JEE Main Physics Questions

**Q1.**Which of the following **cannot** be emitted by radioactive substances during their decay?

(a) Protons

(b) Neutrinoes

(c) Helium nuclei

(d) Electrons

**Q2. **Which of the following four alternatives is not correct? We need modulation:

(a) to reduce the time lag between transmission and reception of the information signal

(b) to reduce the size of antenna

(c) to reduce the fractional band width, that is the ratio of the signal band width to the centre frequency

(d) to increase the selectivity

**Q3. **Which of the following is **incorrect** regarding the first law of thermodynamics?

(a) It is a restatement of the principle of conservation of energy

(b) It is not applicable to any cyclic process

(c) It introduces the concept of the entropy

(d) It introduces the concept of the internal energy

**Q4. **Which of the following is more close to a black body?

(a) black board paint

(b) green leaves

(c) black holes

(d) red roses

**Q5. **Which of the following is used in optical fibres?

(a) total internal reflection

(b) scattering

(c) diffraction

(d) refraction.

**Q6. **Which of the following parameters does not characterize the thermodynamic state of matter?

(a) Temperature

(b) Pressure

(c) Work

(d) Volume

**Q7. **Which of the following radiations has the least wavelength?

(a) γ-rays

(b) β –rays

(c) α -rays

(d) X -rays

**Q8. **Which of the following statements is correct for any thermodynamic system?

(a) The change in entropy can never be zero

(b) Internal energy and entropy and state functions

(c) The internal energy changes in all processes

(d) The work done in an adiabatic process is always zero.

**Q9. **Which of the following statements is **FALSE** for a particle moving in a circle with a constant angular speed?

(a) The acceleration vector points to the centre of the circle ** **(b) The acceleration vector is tangent to the circle

**(c) The velocity vector is tangent to the circle**

**(d) The velocity and acceleration vectors are perpendicular to each other.**

**Q10.**Which of the following transitions in hydrogen atoms emit photons of highest frequency?

(a) n = 1 to n = 2

(b) n = 2 to n = 6

(c) n = 6 to n = 2

(d) n = 2 to n = 1

1.a2.a3.b4.A5.a6.c7.a8.b9.b10.D11.b12.a13.A14.b

**Q11.**Which of the following units denotes the dimension ML

^{2}/Q

^{2}, where Q denotes the electric charge?

(a) Wb/m

^{2}

(b) Henry

(c) H/m

^{2}

(d) Weber (Wb)

**Q12. **Which one of the following represents the correct dimensions of the coefficient of viscosity?

(a) ML^{-1}T^{-1 }(b) MLT^{-1}** **(c) ML

^{-1}T

^{-2}

**(d) ML**

^{-2}T

^{-2}

**Q13.**Which statement is incorrect?

(a) all reversible cycles have same efficiency

(b) reversible cycle has more efficiency than an irreversible one

(c) Carnot cycle is a reversible one

(d) Carnot cycle has the maximum efficiency in all cycles.

**Q14. **While measuring the speed of sound by performing a resonance column experiment, a student gets the first resonance condition at a column length of 18 cm during winter. Repeating the same experiment during summer, she measures the column length to be x cm for the second resonance. Then

(a) 18 > x

(b) x> 54

(c) 54 > x > 36

(d) 36 > x > 18

## JEE Main Physics Practice Test

**Q1.**Two wires are made of the same material and have the same volume. However wire 1 has cross-sectional area A and wire 2 has cross-sectional area 3A. If the length of wire 1 increases by Δx on applying force F, how much force is needed to stretch wire 2 by the same amount?

(a) 4 F

(b) 6 F

(c) 9 F

(d) F

**Q2. **When _{3}Li^{7} nuclei are bombarded by protons, and the resultant nuclei are _{4}Be^{8}, the emitted particles will be

(a) alpha particles

(b) beta particles

(c) gamma photons

(d) neutrons

**Q3. **When a U^{238} nucleus originally at rest, decays by emitting an alpha particle having a speed ‘u’, the recoil speed of the residual nucleus is

(a)

(b)

(c)

(d)

**Q4. **When forces F_{1}, F_{2}, F_{3} are acting on a particle of mass m such that F_{2} and F_{3} are mutually perpendicular, then the particle remains stationary. If the force F_{1} is now removed then the acceleration of the particle is

(a) F_{1} /m ** **(b) F

_{2}F

_{3}/mF

_{1}

**(c) (F**

_{2}– F

_{3})/m

**(d) F**

_{2}/m.

**Q5.**When monochromatic red light is used instead of blue light in a convex lens, its focal length will

(a) increase

(b) decrease

(c) remain same

(d) does not depend on colour of light

**Q6. **When npn transistor is used as an amplifier

(a) electrons move from collector to base

(b) holes move from emitter to base

(c) electrons move from base to collector

(d) holes move from base to emitter

**Q7. **When p-n junction diode is forward biased then

(a) both the depletion region and barrier height are reduced

(b) the depletion region is widened and barrier height is reduced

(c) the depletion region is reduced and barrier height is increased

(d) Both the depletion region and barrier height are increased

**Q8. **When temperature increases, the frequency of a tuning fork

(a) increases

(b) decreases

(c) remains same

(d) increases or decreases depending on the material

**Q9. **When two tuning forks (fork 1 and fork 2) are sounded simultaneously, 4 beats per second are heard. Now, some tape is attached on the prong of the fork2**. **When the tuning forks are sounded again, 6 beats per second are heard. If the frequency of fork 1 is 200 Hz, then what was the original frequency of fork 2?

(a) 202 Hz

(b) 200 Hz

(c) 204 Hz

(d) 196 Hz

**Q10. **Which of the following are not electromagnetic waves?

(a) cosmic rays

(b) gamma rays

(c) β-rays

(d) X-rays.

1.C2.c3.c4.a5.a6.d7.a8.b9.d10.a

** JEE Main Physics Previous Year Questions**

**June 30th, 2017 | Author: admin**

**Q1.**Two identical charged spheres are suspended by strings of equal lengths. The strings make an angle of 30° with each other. When suspended in a liquid of density 0.8g cm^{–3}, the angle remains the same. If density of the material of the sphere is 1.6 g cm^{–3}, the dielectric constant of the liquid is

(a) 4

(b) 3

(c) 2

(d) 1

**Q2. **Two identical charged spheres suspended from a common point by two massless strings of length l are initially a distance d(d << l) apart because of their mutual repulsion. The charge begins to leak from both the spheres at a constant rate. As a result charges approach each other with a velocity v. Then as a function of distance x between them,

(a) v ∝ x^{–1}

(b) v ∝ x^{½}

(c) v ∝ x

(d) v ∝ x^{–½}

**Q3. **Two identical particles move towards each other with velocity 2v and v respectively. The velocity of centre of mass is

(a) v

(b) v/3

(c) v/2

(d) zero.

**Q4. **Two lenses of power –15 D and +5 D are in contact with each other. The focal length of the combination is

(a) + 10 cm

(b) – 20 cm

(c) – 10 cm

(d) + 20 cm

**Q5. **Two mercury drops (each of radius ‘r’) merge to form bigger drop. The surface energy of the bigger drop, if T is the surface tension, is:

(a) 4πr^{2}T

(b) 2 πr^{2}T

(c) 2^{8/3} πr^{2}T

(d) 2^{5/3} πr^{2}T

**Q6. **Two particles are executing simple harmonic motion of the same amplitude A and frequency ω along the x-axis. Their mean position is separated by distance X_{0} (X_{0}> A). If the maximum separation between them is (X_{0} + A), the phase difference between their motion is:

(a) π/3

(b) π/4

(c) π/6

(d) π/2

**Q7. **Two point charges + 8q and – 2q are located at x = 0 and x = L respectively. The location of a point on the x axis at which the net electric field due to these two point charges is zero is

(a) 4/L

(b) 2 L

(c) 4 L

(d) 8 L

**Q8. **Two point white dots are 1 mm apart on a black paper. They are viewed by eye of pupil diameter 3 mm. Approximately, what is the maximum distance at which these dots can be resolved by the eye? (Take wavelength of light = 500 nm)

(a) 1 m

(b) 5 m

(c) 3 m

(d) 6 m

**Q9. **Two sources of equal emf are connected to an external resistance R. The internal resistance of the two sources are R_{1} and R_{2} (R_{1}> R_{1}). If the potential difference across the source having internal resistance R_{2} is zero, then

(a) R = R_{2} – R_{1}

(b) R = R_{2}× (R_{1} + R_{2})/(R_{2} – R_{1}) (c) R = R_{1}R_{2}/(R_{2} – R_{1}) (d) R = R_{1}R_{2}/(R_{1} – R_{2})

**Q10. **Two spherical conductors B and C having equal radii and carrying equal charges on them repel each other with a force F when kept apart at some distance. A third spherical conductor having same radius as that B but **uncharged** is brought in contact with B, then brought in contact with C and finally removed away from both. The new force of repulsion between B and C is

(a) F/8

(b) 3 F/4

(c) F/4

(d) 3 F/8

1.C2.d3.C4.c5.C6.a7.b8.b9.a10.d

** JEE Main Physics Practice Sets**

**June 30th, 2017 | Author: admin**

**Q1.**This questions has Statement I and Statement II. Of the four choices given after the Statements, choose the one that best describes into two Statements.

**Statement-I:** Higher the range, greater is the resistance of ammeter.

**Statement-II:** To increase the range of ammeter, additional shunt needs to be used across it.

(a) Statement-I is true, Statement-II is true, Statement-II is the correct explanation of Statement-I.

(b) Statement-I is true, Statement-II is true, Statement-II is not the correct explanation of Statement-I.

(c) Statement-I is true, Statement-II is false.

(d) Statement-I is false, Statement-II is true.

**Q2. **Three sound waves of equal amplitudes have frequencies (v _{– 1}), v, (v + 1). They superpose to give beats. The number of beats produced per second will be:

(a) 3

(b) 2

(c) 1

(d) 4

**Q3. **Time taken by a 836 W heater to heat one litre of water from 10°C to 40°C is

(a) 150 s

(b) 100 s

(c) 50 s

(d) 200 s

**Q4. **To demonstrate the phenomenon of interference, we require two sources which emit radiation

(a) of nearly the same frequency

(b) of the same frequency

(c) of different wavelengths

(d) of the same frequency and having a definite phase relationship

**Q5. **To get three images of a single object, one should have two plane mirrors at an angle of

(a) 60 °

(b) 90 °

(c) 120 °

(d) 30 °

**Q6. **Two capacitors C_{1} and C_{2} are charged to 120 V and 200 V respectively. It is found that connecting them together the potential on each one can be made zero. Then

(a) 5C_{1} = 3C_{2}

(b) 3C_{1} = 5C_{2}

(c) 3C_{1} + 5C_{2} = 0

(d) 9C_{1} = 4C_{2}

**Q7. **Two cars of mass m_{1} and m_{2} are moving in circles of radii r_{1} and r_{2}, respectively. Their speeds are such that they make complete circles in the same time t. The ratio of their centripetal acceleration is:

(a) m_{1} r_{1}: m_{2} r_{2}** **(b) m

_{1}: m

_{2}

**(c) r**

_{1}: r

_{2}

**(d) 1: 1**

**Q8.**Two coils are placed close to each other. The mitual inductance of the pair of coils depends upon

(a) the rates at which currents are changing in the two coils

(b) relative position and orientation of the two coils

(c) the materials of the wires of the coils

(d) the currents in the two coils

**Q9. **Two electric bulbs marked 25W – 220 V and 100W – 220V are connected in series to a 440 V supply. Which of the bulbs will fuse?

(a) Both

(b) 100 W

(c) 25 W

(d) Neither

**Q10. **Two forces are such that the sum of their magnitudes is 18 N and their resultant is 12 N which is perpendicular to the smaller force. Then the magnitudes of the forces are

(a) 12 N, 6 N ** **(b) 13 N, 5 N

**(c) 10 N, 8 N**

**(d) 16N, 2N.**

**1.d2.b3.a4.d5.b6.b7.c8.b9.c10.b**

** JEE Main Physics Quiz**

**June 30th, 2017 | Author: admin**

**Q1.**The work of 146 kJ is performed in order to compress one kilo mole of gas adiabatically and in this process the temperature of the gas increases by 7°C. The gas is (R = 8.3 J mol^{–1} K^{–1})

(a) diatomic

(b) triatomic

(c) a mixture of monoatomic and diatomic

(d) monoatomic

**Q2. **Themagnetic field in a travelling electromagnetic wave has a peak value of 20 nT. The peak value of electric field strength is:

(a) 3 V/m

(b) 6 V/m

(c) 9 V/m

(d) 12 V/m

**Q3. **This equation has statement 1 and statement 2 of the four choices given the statements, choose the one that describes the two statements.

**Statement 1:** Davisson-Germer experiment established the wave nature of electrons.

**Statement 2:** If electrons have wave nature, they can interfere and show diffraction.

(a) Statement 1 is false, Statement 2 is true.

(b) Statement 1 is true, Statement 2 is false

(c) Statement 1 is true, Statement 2 is true, Statement 2 is the correct explanation for statement 1

(d) Statement 1 is true, Statement 2 is true, Statement 2 is not the correct explanation of Statement 1

**Q4. **This question contains Statement-1 and Statement-2. Of the four choices given after the statements, choose the one that best describes the two statements.

**Statement-1:** For a charged particle moving from point P to point Q, the net work done by an electrostatic field on the particle is independent of the path connecting point P to point Q.

**Statement-2:** The net work done by a conservative force on an object moving along a closed loop is zero.

(a) Statement-1 is true, Statement-2 is true; Statement-2 is the correct explanation of Statement-1.

(b) Statement-1 is true, Statement-2 is true; Statement-2 is not the correct explanation of Statement-1.

(c) Statement-1 is false, Statement-2 is true.

(d) Statement-1 is true, Statement-2 is false.

**Q5. **This question contains Statement-1 and Statement-2. Of the four choices given after the statements, choose the one that best describes the two statements.

**Statement-1**:

For a mass M kept at the centre of a cube of side ‘a’, the flux of gravitational field passing through its sides 4 π GM.

and

**Statement-2:**

If the direction of a field due to a point source is radial and its dependence on the distance ‘r’ from the source is given as 1/r^{2} , its flux through a closed surface depends only on the strength of the source enclosed by the surface and not on the size or shape of the surface.

(a) Statement -1 is false, Statement-2 is true

(b) Statement -1 is true, Statement-2 is true; Statement -2 is a correct explanation for Statement-1

(c) Statement -1 is true, Statement-2 is true; Statement -2 is not a correct explanation for Statement-1

(d) Statement -1 is true, Statement-2 is false

**Q6. **This question contains Statement-1 and statement-2. Of the four choices given after the statements, choose the one that best describes the two statements.

**Statement-1:** Energy is released when heavy nuclei undergo fission or light nuclei undergo fusion and

**Statement-2:** For heavy nuclei, binding energy per nucleon increases with increasing Z while for light nuclei it decreases with increasing Z.

(a) Statement-1 is false, Statement-2 is true

(b) Statement-1 is true, Statement-2 is true; Statement-2 is a correct explanation for Statement-1

(c) Statement-1 is true, Statement-2 is true; Statement-2 is not a correct explanation for Statement-1

(d) Statement-1 is true, Statement-2 is false

**Q7. **This question has a paragraph followed by two statements, Statement – 1 and Statement –2**. **Of the given four alternatives after the statements, choose the one that describes the statements.

A thin air film is formed by putting the convex surface of a plane-convex lens over a plane glass plate. With monochromatic light, this film gives an interference pattern due to light reflected from the top (convex) surface and the bottom (glass plate) surface of the film.

**Statement – 1:** When light reflects from the air-glass plate interface, the reflected wave suffers a phase change of π.

**Statement – 2:** The centre of the interference pattern is dark.

(a) Statement – 1 is true, Statement – 2 is true, Statement – 2 is the correct explanation of Statement – 1.

(b) Statement – 1 is true, Statement – 2 is true, Statement – 2 is not the correct explanation of Statement – 1.

(c) Statement – 1 is false, Statement – 2 is true.

(d) Statement – 1 is true, Statement – 2 is false.

**Q8. **This question has Statement – 1 and Statement –2. Of the four choices given after the statements, choose the one that best describes the two statements.

**Statement – 1**: Sky wave signals are used for long distance radio communication. These signals are in general, less stable than ground wave signals.

**Statement – 2:** The state of ionosphere varies from hour to hour, day to day and season to season.

(a) Statement–1 is true, Statement–2 is true, Statement–2 is the correct explanation of Statement–1.

(b) Statement–1 is true, Statement–2 is true, Statement–2 is not the correct explanation of Statement – 1.

(c) Statement – 1 is false, Statement – 2 is true.

(d) Statement – 1 is true, Statement – 2 is false.

**Q9. **This question has Statement – 1 and Statement – 2. Of the four choices given after the statements, choose the one that best describes the two statements.

**Statement – 1:** A metallic surface is irradiated by a monochromatic light of frequency v >v_{ο} (the threshold frequency). The maximum kinetic energy and the stopping potential are K_{max} and V_{ο} respectively. If the frequency incident on the surface is doubled, both the K_{max} and V_{ο} are also doubled.

**Statement – 2:** The maximum kinetic energy and the stopping potential of photoelectrons emitted from a surface are linearly dependent on the frequency of incident light.

(a) Statement–1 is true, Statement–2 is true, Statement – 2 is the correct explanation of Statement – 1.

(b) Statement–1 is true, Statement–2 is true, Statement – 2 is not the correct explanation of Statement – 1.

(c) Statement – 1 is false, Statement – 2 is true.

(d) Statement – 1 is true, Statement – 2 is false.

**Q10. **This question has Statement 1 and Statement 2**. **Of the four choices given after the Statements, choose the one that best describes the two Statements.

If two springs S_{1} and S_{2} of force constants k_{1} and k_{2}, respectively, are stretched by the same force, it is found that more work is done on spring S_{1} than on spring S_{2}.

**Statement 1**: If stretched by the same amount work done on S_{1}

**Statement 2**: k_{1}<k_{2}

(a) Statement 1 is false, Statement 2 is true. ** **(b) Statement 1 is true, Statement 2 is false.

**(c) Statement 1 is true, Statement 2 is true, Statement 2 is the correct explanation for Statement 1**

**(d) Statement 1 is true, Statement 2 is true, Statement 2 is not the correct explanation for Statement 1**

**1.a2.b3.c4.a5.b6.d7.b8.b9.c10.b**

** JEE Main Physics Questions**

**June 30th, 2017 | Author: admin**

**Q1.**The termistors are usually made of

(a) metal oxides with high temperature coefficient of resistivity

(b) metals with high temperature coefficient of resistivity

(c) metals with low temperature coefficient of resistivity

(d) semiconducting materials having low temperature coefficient of resistivity

**Q2. **The thermo e.m.f. of a thermo -couple is 25 Μv/^{o} C at room temperature. A galvanometer of 40 ohm resistance, capable of detecting current as low as 10^{–5} A, is connected with the thermo couple. The smallest temperature difference that can be detected by this system is

(a) 16^{o} C

(b) 12^{ o} C

(c) 8^{ o} C

(d) 20^{ o} C

**Q3. **The thermo emf of a thermocouple varies with the temperature θ of the hot junction as E = aθ + bθ in volts where the ratio a/b is 700°C. If the cold junction is kept at 0°C, then the neutral temperature is

(a) 1400°C

(b) 350°C

(c) 700°C

(d) No neutral temperature is possible for this termocouple.

**Q4. **The threshold frequency for a metallic surface corresponds to an energy of 6.2 eV and the stopping potential for a radiation incident on this surface is 5 V. The incident radiation lies in

(a) ultra-violet region

(b) infra-red region

(c) visible region

(d) X-ray region

**Q5. **The time period of a satellite of earth is 5 hours. If the separation between the earth and the satellite is increased to 4 times the previous value, the new time period will become

(a) 10 hours

(b) 80 hours

(c) 40 hours

(d) 20 hours

**Q6. **The time period of an earth satellite in circular orbit is independent of

(a) both the mass and radius of the orbit

(b) radius of its orbit

(c) the mass of the satellite

(d) neither the mass of the satellite nor the radius of its orbit.

**Q7. **The total energy of a particle, executing simple harmonic motion is

(a) independent of x

(b) ∝ x^{2}

(c) ∝ x

(d) ∝ x^{1/2}

**Q8. **The transition from the state n = 4 to n = 3 in a hydrogen like atom results in ultraviolet radiation. Infrared radiation will be obtained in the transition from:

(a) 3 → 2

(b) 4 → 2

(c) 5 → 4

(d) 2 → 1

**Q9. **The velocity of a particle is v = v_{0} + gt + ft^{2}. If its position is x = 0 at t = 0, then its displacement after unit time (t = 1) is

(a) v_{0} + g/2 + f ** **(b) v

_{0}+ 2g + 3f

**(c) v**

_{0}+ g/2 + f/3

**(d) v**

_{0}+ g + f

**Q10.**The work function of a substance is 4.0 eV. The longest wavelength of light that can cause photoelectron emission from this substance is approximately.

(a) 310 nm

(b) 400 nm

(c) 540 nm

(d) 220 nm

1.a2.a3.d4.a5.c6.c7.a8.c9.c10.a

** IIT Main Physics Practice Test**

**June 30th, 2017 | Author: admin**

**Q1.**The ‘rad’ is the correct unit used to report the measurement of

(a) the ability of a beam of gamma ray photons to produce ions in a target

(b) the energy delivered by radiation to a target

(c) the biological effect of radiation

(d) the rate of decay of a radioactive source

**Q2. **The refractive index of a glass is 1.520 for red light and 1.525 for blue light. Let D_{1} and D_{2} be angles of minimum deviation for red and blue light respectively in a prism of this glass. Then,

(a) D_{1}< D_{2}

(b) D_{1} = D_{2}

(c) D_{1} can be less than or greater than D_{2} depending upon the angle of prism

(d) D_{1}> D_{2}

**Q3. **The relation between time t and distance x is t = ax^{2} + bx where a and b are constants. The acceleration is

(a) 2bv^{3}** **(b) -2abv

^{2}

**(c) 2av**

^{2}

**(d) -2av**

^{3}

**Q4.**The resistance of a bulb filmanet is 100Ω at a temperature of 100°C. If its temperature coefficient of resistance be 0.005 per °C, its resistance will become 200 Ω at a temperature of

(a) 300°C

(b) 400°C

(c) 500°C

(d) 200°C

**Q5. **The resistance of a wire is 5 ohm at 50°C and 6 ohm at 100°C. The resistance of the wire at 0°C will be

(a) 3 ohm

(b) 2 ohm

(c) 1 ohm

(d) 4 ohm

**Q6. **The resistance of hot tungsten filament is about 10 times the cold resistance. What will be the resistance of 100 W and 200 V lamp when not in use?

(a) 20Ω

(b) 40Ω

(c) 200Ω

(d) 400Ω

**Q7. **The resistance of the series combination of two resistances is S. when they are joined in parallel the total resistance is P. If S = nP then the Minimum possible value of n is

(a) 2

(b) 3

(c) 4

(d) 1

**Q8. **The self inductance of the motor of an electric fan is 10 H. In order to impart maximum power at 50 Hz, it should be connected to a capacitance of

(a) 8μF

(b) 4μF

(c) 2μF

(d) 1μF

**Q9. **The speed of sound in oxygen (O_{2}) at a certain temperature is 460 ms^{–1}. The speed of sound in helium (He) at the same temperature will be (assume both gases to be ideal)

(a) 1421 ms^{–1}

(b) 500 ms^{–1}

(c) 650 ms^{–1}

(d) 330 ms^{–1}

**Q10. **The supply voltage to room is 120V. The resistance of the lead wires is 6 Ω. A 60 W bulb is already switched on. What is the decrease of voltage across the bulb, when a 240 W heater is switched on in parallel to the bulb?

(a) zero

(b) 2.9 Volt

(c) 13.3 Volt

(d) 10.04 Volt

1.c2.a3.d4.b5.d6.b7.c8.d9.a10.d

** IIT Main Physics Previous Year Questions**

**June 30th, 2017 | Author: admin**

**Q1.**The length of a simple pendulum executing simple harmonic motion is increased by 21%. The percentage increase in the time period of the pendulum of increased length is

(a) 11%

(b) 21%

(c) 42%

(d) 10%

**Q2. **The manifestation of band structure in solids is due to

(a) Bohr’s correspondence principle

(b) Pauli’s exclusion principle

(c) Heisenberg’s uncertainty principle

(d) Boltzmann’s law

**Q3. **The maximum number of possible interference maxima for slit-separation equal to twice the wavelength in Young’s double-slit experiment is

(a) three

(b) five

(c) infinite

(d) zero

**Q4. **The minimum force required to start pushing a body up rough (frictional coefficient μ) inclined plane is F_{1} while the minimum force needed to prevent it from sliding down is F_{2}. If the inclined plane makes an angle θ from the horizontal such that tan θ = 2 μ then the ratio F_{1}/F_{2} is

(a) 1 ** **(b) 2

**(c) 3**

**(d) 4**

**Q5.**The minimum velocity (in ms

^{–1}) with which a car driver must traverse a flat curve of radius 150 m and coefficient of friction 0.6 to avoid skidding is

(a) 60

(b) 30

(c) 15

(d) 25

**Q6. **The negative Zn pole of a Daniell cell, sending a constant current through a circuit, decreases in mass by 0.13g in 30 minutes. If the electeochemical equivalent of Zn and Cu are 32.5 and 31.5 respectively, the increase in the mass of the positive Cu pole in this time is

(a) 0.180 g

(b) 0.141g

(c) 0.126 g

(d) 0.242 g

**Q7. **The output of an OR gate is connected to both the inputs of a NAND gate. The combination will serve as a:

(a) NOT gate

(b) NOR gate

(c) AND gate

(d) OR gate

**Q8. **The part of a transistor which is most heavily doped to produce large number of majority carriers is

(a) emmiter

(b) base

(c) collector

(d) can be any of the above three.

**Q9. **The phase difference between the alternating current and emf is π/2. Which of the following cannot be the constituent of the circuit?

(a) R, L

(b) C alone

(c) L alone

(d) L, C

**Q10. **The physical quantities not having same dimensions are

(a) torque and work** **(b) momentum and planck’s constant

**(c) stress and young’s modulus**

**(d) speed and (m**

_{0}e

_{0})

^{-1/2}

**1.d2.b3.b4.c5.B6.c7.b8.a9.a10.b**

** IIT Main Physics Practice Sets**

**June 30th, 2017 | Author: admin**

**Q1.**The escape velocity of a body depends upon mass as

(a) m^{0}

(b) m^{1}

(c) m^{2}

(d) m^{3}

**Q2. **The function sin^{2} (ωt) represents

(a) a periodic, but not simple harmonic motion with a period π/ω

(b) a periodic, but not simple harmonic motion with a period 2π/ω

(c) a simple harmonic motion with a period π/ω

(d) a simple harmonic motion with a period 2π/ω

**Q3. **The half life of a radioactive substance is 20 minutes. The approximate time interval (t_{2} – t_{1}) between the time t_{2} when 2/3 of it had decayed and time t_{1} when 1/3 of it had decayed is:

(a) 14 min

(b) 20 min

(c) 28 min

(d) 7 min

**Q4. **The half-life period of a radio-active element X is same as the mean life time of another radio-active element Y. Initially they have the same number of atoms. Then

(a) X and Y decay at same rate always

(b) X will decay faster than Y

(c) Y will decay faster than X

(d) X and Y have same decay rate initially

**Q5. **The height at which the acceleration due to gravity becomes g/9 (where g = the acceleration due to gravity on the surface of the earth) in terms of R, the radius of the earth, is:

(a) R/√2

(b) R/2

(c) √2R

(d) 2 R

**Q6. **The image formed by an objective of a compound microscope is

(a) virtual and diminished

(b) real and diminished

(c) real and enlarged

(d) virtual and enlarged

**Q7. **The intensity of gamma radiation from a given source is I. On passing through 36 mm of lead, it is reduced to I/8. The thickness of lead which will reduce the intensity to I/2 will be

(a) 9 mm

(b) 6 mm

(c) 12 mm

(d) 18 mm

**Q8. **The kinetic energy needed to project a body of mass m from the earth surface (radius R) to infinity is

(a) mgR/2

(b) 2mgR

(c) mgR

(d) mgR/4.

**Q9. **The Kirchhoff’s first law (Σi = 0) and second law (ΣiR = ΣE), where the symbols have their usual meanings, are respectively based on

(a) conservation of charge, conservation of momentum

(b) conservation of energy, conservation of charge

(c) conservation of momentum, conservation of charge

(d) conservation of charge, conservatrion of energy

**Q10. **The length of a given cylindrical wire is increased by 100%. Due to the consequent decrease in diameter the change in the resistance of the wire will be

(a) 200%

(b) 100%

(c) 50%

(d) 300%

1.a2.c3.b4.c5.d6.c7.c8.c9.d10.d

** IIT Main Physics Quiz**

**June 30th, 2017 | Author: admin**

**Q1.**The bob of a simple pendulum is a spherical hollow ball filled with water. A plugged hole near the bottom of the oscillating bob gets suddenly unplugged. During observation, till water is coming out, the time period of oscillation would

(a) first decrease and then increase to the original value

(b) first increase and then decrease to the original value

(c) increase towards a saturation value

(d) remain unchanged

**Q2. **The change in the value of ‘g’ at a height ‘h’ above the surface of the earth is the same as at a depth ‘d’ below the surface of earth. When both ‘d’ and ‘h’ are much smaller than the radius of earth, then which one of the following is correct?

(a) d = 3h/2

(b) d = h/2

(c) d = h

(d) d = 2 h

**Q3. **The core of any transformer is laminated so as to

(a) reduce the energy loss due to eddy currents

(b) make it light weight

(c) make it robust and strong

(d) increase the secondary voltage

**Q4. **The current in the primary circuit of a potentiometer is 0.2 A. The specific resistance and cross-section of the potentiometer wire are 4 × 10^{–7} ohm metre and 8 × 10^{–7} m^{2}, respectively. The potential gradient will be equal to

(a) 1 V /m

(b) 0.5V/m

(c) 0.1 V/m

(d) 0.2 V/m

**Q5. **The difference in the variation of resistance with temeperature in a metal and a semiconductor arises essentially due to the difference in the

(a) crystalsturcture

(b) variation of the number of charge carriers with temperature

(c) type of bonding

(d) variation of scattering mechanism with temperature

**Q6. **The dimension of magnetic field in M, L, T and C (coulomb) is given as

(a) ML**T ^{–1}** C

^{–1}

**(b) MT**

^{2}C

^{–2}

**(c) M**

**T**C

^{–1}^{–1}

**(d) MT**

^{–2}C

^{–1}

**Q7.**The displacement of a particle varies according to the relation x = 4(cos πt + sin πt). The amplitude of the particle is

(a) – 4

(b) 4

(c) 4√2

(d) 8

**Q8. **The earth radiates in the infra-red region of the spectrum. The spectrum is correctly given by

(a) Rayleigh Jeans law

(b) Planck’s law of radiation

(c) Stefan’s law of radiation

(d) Wien’s law

**Q9. **The energy band gap is maximum in

(a) metals

(b) superconductors

(c) insulators

(d) semiconductors.

**Q10. **The escape velocity for a body projected vertically upwards from the surface of earth is 11 km/s. If the body is projected at an angle of 45°with the vertical, the escape velocity will be

(a) 11√2 km/s

(b) 22 km/s

(c) 11 km/s

(d) 11/√2 km/s

1.b2.d3.a4.c5.b6.c7.c8.d9.c10.c