JEE Main Physics Mock - 1


25 Questions MCQ Test Mock Test Series for JEE Main & Advanced 2021 | JEE Main Physics Mock - 1


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This mock test of JEE Main Physics Mock - 1 for JEE helps you for every JEE entrance exam. This contains 25 Multiple Choice Questions for JEE JEE Main Physics Mock - 1 (mcq) to study with solutions a complete question bank. The solved questions answers in this JEE Main Physics Mock - 1 quiz give you a good mix of easy questions and tough questions. JEE students definitely take this JEE Main Physics Mock - 1 exercise for a better result in the exam. You can find other JEE Main Physics Mock - 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:

Answer :- c

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-
Assertion(A):All radio-active elements are finally converted into lead.
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:
*Answer can only contain numeric values
QUESTION: 21

The orbital velocity of an artificial satellite in a circular orbit just above the earth’s surface is v0. The orbital velocity of satellite orbiting at an altitude of double the radius of earth is V0/√n Then the value of n is :


Solution:

*Answer can only contain numeric values
QUESTION: 22

A 300 W carrier is modulated to a depth 75%. The total power in the modulated wave is:-


Solution:

*Answer can only contain numeric values
QUESTION: 23

A conducting rod of 1 m length and 1 kg mass is suspended by two vertical wires through its ends. An external magnetic field of 2T is applied normal to the rod. Now, the current to be passed through the rod so as to make the tension in the wires zero is : (Take g = 10 ms–2) :-


Solution:

Magnetic force on rod = BIℓ
Weight of the rod = mg
For no tension in wire, BIℓ = mg

*Answer can only contain numeric values
QUESTION: 24

At what speed a ball must be projected vertically upward so that distance travelled by it in 5th second is equal to distance travelled in sixth second (in m/s):-


Solution:

time of flight = (5 sec) × 2 = 10 sec
µ = gt = 9.8 × 5 = 49 m/s

*Answer can only contain numeric values
QUESTION: 25

In thermodynamic process pressure of a fixed mass of gas is changed in such a manner that the gas releases 30 joule of heat and 18 joule of work was done on the gas. If the initial internal energy of the gas was 60 joule, then, the final internal energy (in J) will be:


Solution:

ΔQ = –30J
Δw = –18
Ui = 60 J
Uf = ?
ΔQ = Δw + Uf – Ui
–30 = –18 + Uf – 60 ⇒ Uf = 48 J

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