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# JEE(MAIN) Physics Mock Test - 1

## 30 Questions MCQ Test JEE Main Mock Test Series 2020 & Previous Year Papers | JEE(MAIN) Physics Mock Test - 1

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

### An electric lamp is connected to 220 V, 50 Hz supply. Then the peak value of voltage is

Solution:

Solution :- V(0) = Vrms × 2

= 220 × √2

= 310

QUESTION: 2

### In a step-up transformer the voltage in the primary is 220 V and the current is 5A. The secondary voltage is found to be 22000V. The current in the secondary (neglect losses) is

Solution: QUESTION: 3

### A body moves along a circular path of radius 10 m and the coefficient of friction is 0.5. What should be the angular velocity of the body, if it is not to slip on the surface?

Solution: QUESTION: 4
K.E. of emitted cathode rays is dependent on
Solution:
QUESTION: 5

A semi circle arc of radius 'a' is charged uniformly and the charge per unit length is λ. The electric field at its centre is

Solution:
QUESTION: 6

A gun fires the bullets each of mass 10 g with a velocity of 50 m−s-1. If 1000 bullets are fired per second, then thrust on the shoulder will be

Solution:
QUESTION: 7

An electric dipole is placed along the X-axis at the origin O. A point P is at a distance of 20 cm from this origin such that OP makes an angle π/3 with the X axis. If electric field at P makes an angle θ with X-axis, the value of θ is

Solution:    QUESTION: 8

A metre stick AB hinged (without friction) at the end A as shown in the figure is kept horizontal by means of a string tied to the end B, the other end of the string being tied to a hook. The string is carefully cut (or burnt), and the scale executes angular oscillations about an axis passing through the end A. What is the speed of the end B when the metre stick assumes vertical position immediately after the string is burnt? (Acceleration due to gravity = 10 ms–2) Solution: The centre of gravity of the metre stick is at its middle. When the string is burnt, the height of the centre of gravity is reduced by 0.5 m, thereby reducing the gravitational potential energy of the metre stick by MghM×10×0.5 = 5joule, where M is the mass of the metre stick.

The decrease in the potential energy is equal to the increase in kinetic energy. Therefore in the vertical position of the metre stick, its kinetic energy

(½)Iω2 = 5M

Since the moment of inertia of a uniform bar of length about a normal axis through ite mid point is ML2/12, its moment of inertia about a parallel axis through its end is ML2/3. [You will get this by applying the parallel axis theorem (see the post dated 2oth January 2008)]

Therefore, we have (½)(ML2/3)ω2 = 5M

Since ω = v/L and L = 1 metre, the above equation becomes

v2/6 = 5, from which = √30 = 5.4 ms–1 (approximately).

QUESTION: 9

The symbolic representation of four logic gates are given below:    The logic symbols for OR, NOT and NAND gates are respectively:

Solution:
QUESTION: 10
In a capillary tube, water rises upto 3 mm. The height of water that will rise in another capillary tube having one-third radius of the first is
Solution:
QUESTION: 11

If a long hollow copper pipe carries a current then magnetic field produced will be

Solution: QUESTION: 12
A chain reaction is fission of uranium is possible because
Solution:
QUESTION: 13

Two bodies of mass 10 kg and 5 kg moving in concentric orbits of radii R and r such that their periods are the same. Then the ratio between their centripetal acceleration is

Solution: QUESTION: 14
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):When there is an electric current through a conducting wire along its length, then an electric field must exist insire the wire but parallel to it.
Reason(R): Electric current flows through a wire due to flow of electrons.
Solution:
QUESTION: 15
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-
Reason(R):Radioactive elements emit α-particles, β-particles and γ-rays.
Solution:
QUESTION: 16
The moment of inertia of a uniform disc about an axis passing through its centre and perpendicular to its plane is 1kg - m2. It is rotating with an angular velocity 100 radians/second. Another identical disc is gently placed on it so that their centres coincide. Now these two discs together continue to rotate about the same axis. Then the loss in kinetic energy in kilo joules is
Solution:
QUESTION: 17

The internal energy of the gas increases when

Solution:

When a gas expands adiabatically, it loses internal energy equal to the work done by the gas. In this case the temperature of the gas decreases.

When a gas is compressed adiabatically, it gains internal energy equal to the work done on the gas. In this case the temperature of the gas increases.

QUESTION: 18

The dimensional equation for magnetic flux is

Solution: QUESTION: 19

If T is the reverberation time of an auditorium of volume V, then

Solution:

Generally reverberation time is proportional to linear dimensions of the room. Hence, it will be proportional to the volume of the room.

QUESTION: 20

The figure shows an energy level diagram for the hydrogen atom. Several transition are marked as I, II, III,........ . The diagram is only indicative and not to scale. Q. The wavelength of the radiation involved in transition II is -

Solution:
QUESTION: 21

The figure shows an energy level diagram for the hydrogen atom. Several transition are marked as I, II, III,........ . The diagram is only indicative and not to scale. Q. In which transition is a Balmer series photon absorbed?

Solution:
QUESTION: 22 The figure shows a surface XY separating two transparent media, medium – 1 and medium – 2. The lines ab and cd represent wavefronts of light wave traveling in medium – 1 and incident on XY. The lines ef and gh represents wavefronts of the light wave in medium – 2 after refraction.
Based upon above paragraph answer the following questions.

Q. Light travels as a

Solution:
QUESTION: 23 The figure shows a surface XY separating two transparent media, medium – 1 and medium – 2. The lines ab and cd represent wavefronts of light wave traveling in medium – 1 and incident on XY. The lines ef and gh represents wavefronts of the light wave in medium – 2 after refraction.
Based upon above paragraph answer the following questions.

Q. The phase of the light wave at c, d, e and f are φc, φd, φe and φ respectively. It is given that φc ≠ φf.

Solution:

Points c and d areon the same wavefront. Therefore, φc = φd
Similarly;  φe = φ. Thus,  (φd−φf) = (φc −φe)

QUESTION: 24 The figure shows a surface XY separating two transparent media, medium – 1 and medium – 2. The lines ab and cd represent wavefronts of light wave traveling in medium – 1 and incident on XY. The lines ef and gh represents wavefronts of the light wave in medium – 2 after refraction.
Based upon above paragraph answer the following questions.

Q. Speed of light is

Solution:
QUESTION: 25

If the velocity of light is 3 x 108 m s − 1 , the wavelength in nanometer of soft X - rays of frequency 2 x 1017 Hz is

Solution:
QUESTION: 26

Energy per unit volume for a capacitor having area A and separation d kept at potential difference V is given by

Solution:  QUESTION: 27

A conical pendulum, made up of a thin uniform rod of length l and mass m, rotates uniformly about a vertical axis, with angular velocity ω . The upper end of the rod is hinged. The angle θ made by the rod with the vertical is

Solution:

Let us consider the system in a frame rotating with the rod. In this frame, the rod is at rest and experiences not only the gravitational force m vector g and the reaction force vector R, but also the centrifugal force vector Fcf

In the considered frame, from the condition of equilibrium i.e. Noz=0 or, Ncf=mg l/2sinθ   .......(1)

where Ncf is the moment of centrifugal force about O. To calculate Ncf,  let us consider an element of length dx, situated at a distance x from the point O. This element is subjected to a horizontal pseudo force (m/l) dxω2xsinθ.

The moment of this pseudo force about the axis of rotation through the point O is QUESTION: 28

Three cells each of e.m.f. 1.5 V and internal resistance 1 Ω are connected in parallel. What would be the e.m.f. of the combination ?

Solution:
QUESTION: 29

A parallel plate capacitor is charged using a battery, and the battery is then removed. The plates of the capacitor are then brought closer together. Which of the following statements is false?

Solution:
QUESTION: 30

A 10 A ammeter has a resistance of 0.09 Ω. What resistance of the shunt will enable it to read up to 100 A?

Solution: 