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# JEE(MAIN) Physics Mock Test - 4

## 30 Questions MCQ Test JEE Main Mock Test Series 2020 & Previous Year Papers | JEE(MAIN) Physics Mock Test - 4

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This mock test of JEE(MAIN) Physics Mock Test - 4 for JEE helps you for every JEE entrance exam. This contains 30 Multiple Choice Questions for JEE JEE(MAIN) Physics Mock Test - 4 (mcq) to study with solutions a complete question bank. The solved questions answers in this JEE(MAIN) Physics Mock Test - 4 quiz give you a good mix of easy questions and tough questions. JEE students definitely take this JEE(MAIN) Physics Mock Test - 4 exercise for a better result in the exam. You can find other JEE(MAIN) Physics Mock Test - 4 extra questions, long questions & short questions for JEE on EduRev as well by searching above.
QUESTION: 1

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QUESTION: 2

Solution:
QUESTION: 3

### For a given material, the Young's modulus is 2.4 times that of rigidity modulus. Its Poisson's ratio is

Solution: QUESTION: 4
Two spherical conductors of radii 4 cm and 5 cm are charged to the same potential. If σ₁ and σ₂ be the respective values of the surface density of charge on both the conductors, then the ratio σ₁/σ₂ is
Solution:
QUESTION: 5

If 3.8 x 10-6 is added to 4.2 x 10-5 giving due regard to significant figures, then the result will be

Solution:
QUESTION: 6
A transformer is used to reduce the mains supply of 220 V to 11 V. If the currents in primary and secondary coils are 5 A and 90 A respectively, efficiency of transformer is
Solution: Efficiency= (output power/input power)*100
=>(90*11/220*5)*100
90%
QUESTION: 7

A parallel plate capacitor is first charged and then a dielectric slab is introduced between the plates after disconnecting it from the battery. The quantity that remains unchanged is

Solution:
QUESTION: 8
Spot the wrong statement : The acceleration due to gravity decreases if
Solution:
QUESTION: 9
For Boyle's law to hold the gas should be
Solution:
QUESTION: 10

When two deuterium nuclei fuse together, in addition to tritium, we get a

Solution: QUESTION: 11

If two bodies are projected at 30o and 60o respectively, with the same velocity, then

Solution:
QUESTION: 12
In the following question, a Statement of Assertion (A) is given followed by a corresponding Reason (R) just below it. Read the Statements carefully and mark the correct answer-
Assertion(A): A uniform solid cylinder rolling with angular velocity ω along a plane surface strikes a vertical rigid wall. Angular velocity of cylinder when it begins to roll up a wall is less than the initial Angular velocity (ω).
Reason(R): After striking the vertical wall angular velocity increases.
Solution:
QUESTION: 13
In the following question, a Statement of Assertion (A) is given followed by a corresponding Reason (R) just below it. Read the Statements carefully and mark the correct answer-
Assertion(A): Current is passed through a metallic wire heating it red. When cold water is poured on half of its portion, the rest of half portion becomes more hot.
Reason(R): Resistance decreases due to decrease in temperature and then current through wire increases.
Solution:
QUESTION: 14
A disc is placed on a surface of pond which has refractive index 5/3. A source of light is placed 4 m below the surface of liquid. The minimum radius of disc needed so that light is not coming out is
Solution:
QUESTION: 15
Sound waves transfer
Solution:
QUESTION: 16

The wavelength of ultrasonic waves in air is of the order of

Solution:
QUESTION: 17

70 calories of heat are required to raise the temperature of 2 moles of an ideal gas at constant pressure from 30oC to 35oC. The amount of heat required to raise the temperature of the same sample of the gas through the same range at constant volume is nearly (Gas constant = 1.99 cal/K-mole)

Solution:
Cp= q/n*delta t
= 70/2*5=7
We know that for diatomic gas
Cp/Cv=7/5
So Cv=5
Cv=q/n*delta t
5=q/2*5
q=50 calories
QUESTION: 18
Both light and sound waves produce diffraction. It is more difficult to observe the diffraction with light waves because
Solution:
QUESTION: 19

A boy of mass 42 Kg eats bananas of 980 calories. If this energy is used up to lift him from the ground, the height to which he can move up is

Solution:

Height = h.
Potential Energy (P.E) = 980 Calories = 4100.32 Jule
Now P.E = mgh
4100.32 = 42 x 9.8 x h
h = 4100.32/42x9.8 ≈ 10m

QUESTION: 20

In the given circuit the capacitor (C) may be charged through resistance R by battery V by closing switch S1. Also when S1 is opened and S2 is closed the capacitor is connected in series with inductor (L). Q. At the start, the capacitor was uncharged. When switch S1 is closed and S2 is kept open, the time constant of this circuit is τ. Which of the following is correct?

Solution:
QUESTION: 21

In the given circuit the capacitor (C) may be charged through resistance R by battery V by closing switch S1. Also when S1 is opened and S2 is closed the capacitor is connected in series with inductor (L). Q. When the capacitor gets charged completely, S1 is opened and S2 is closed. Then,

Solution:
QUESTION: 22

In the given circuit the capacitor (C) may be charged through resistance R by battery V by closing switch S1. Also when S1 is opened and S2 is closed the capacitor is connected in series with inductor (L). Q. Given that the total charged stored in the LC circuit is Q0, for t≥0, the charge on the capacitor is

Solution:
QUESTION: 23

One of the most powerful formulae used in nuclear physics laboratories is the Lorentz force formula applied in cyclotrons, mass spectrographs and identification of fundamental particle.If only a magnetic field is applied to a charge moving with velocity v, the force is given by F = qv×B

Q. The force acting on a charge at rest due to a powerful magnetic field is

Solution:
QUESTION: 24

One of the most powerful formulae used in nuclear physics laboratories is the Lorentz force formula applied in cyclotrons, mass spectrographs and identification of fundamental particle.

If only a magnetic field is applied to a charge moving with velocity v, the force is given by F = qv×BF = qv×B.

Q. The cyclotron frequency

Solution:
QUESTION: 25

One mole of an ideal gas at temperature T was cooled isochorically till the gas pressure fell from P to P/n . Then, by an isobaric process, the gas was restored to the initial temperature. The net amount of heat absorbed by the gas in the process is

Solution: QUESTION: 26

One end of a string of length L is tied to the celling of a lift accelerating upwards with an acceleration 3g. The other end of the string is free. The linear mass density of the string varies linearly from 0 to λ - from bottom to top. Mark out the correct statement for a wave pulse travelling on the string.

Solution:
QUESTION: 27

A metal block of area 0.10 m2 is connected to a 0.010 kg mass by an ideal string which passes over an ideal pulley. See the figure. A liquid with a film thickness of 0.30 mm is placed between the block and the table. If the block moves to the right with a speed of 0.085 m/s, the coefficient of viscosity of the liquid is Solution:
QUESTION: 28

The wire loop PQRSP formed by joining two semi-circular wires of radii R1 and R2 as shown in the fig. below caries a current i. The magnitude of the magnetic induction at the centre C of the loop is Solution:
QUESTION: 29

The length and breadth of a metal sheet are 3.124 m and 3.002 m respectively. The area of this sheet up to four correct significant figures is

Solution:
QUESTION: 30

The significant figures in 300.500 are

Solution: