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# JEE Main Physics Mock - 7

## 25 Questions MCQ Test Mock Test Series for JEE Main & Advanced 2022 | JEE Main Physics Mock - 7

Description
This mock test of JEE Main Physics Mock - 7 for JEE helps you for every JEE entrance exam. This contains 25 Multiple Choice Questions for JEE JEE Main Physics Mock - 7 (mcq) to study with solutions a complete question bank. The solved questions answers in this JEE Main Physics Mock - 7 quiz give you a good mix of easy questions and tough questions. JEE students definitely take this JEE Main Physics Mock - 7 exercise for a better result in the exam. You can find other JEE Main Physics Mock - 7 extra questions, long questions & short questions for JEE on EduRev as well by searching above.
QUESTION: 1

Solution:
QUESTION: 2

### A hotwire ammeter reads 10 A in a a.c. circuit. The peak value of the current is

Solution:

Hot wire ammeter always gives rms value of current, i.e.,
Irms = 10 amp. as Irms = I0/√2

hence I= √2 Irms = √2 x 10 amp = 10√2 A

QUESTION: 3

### The average acceleration vector for a particle having a uniform circular motion is

Solution: In uniform circular motion (UCM), the direction of the acceleration vector points toward the centre of the circle. However, it constantly changes with time. The average of these vectors over one cycle is a null vector.
QUESTION: 4
The X-rays beams coming from an X-ray tube will be
Solution:
QUESTION: 5

A dipole of dipole moment p̅ is placed in uniform electric field E̅, then torque acting on it is given by

Solution:
QUESTION: 6
When two surfaces are coated with a lubricant, then they
Solution:
QUESTION: 7
Two pieces of a glass plate, placed one upon the other with a little water in between them, can not be separated easily, because of
Solution:
QUESTION: 8

The gyromagnetic ratio of an electron of charge e and mass m is equal to

Solution:
QUESTION: 9
If the momentum of a body increases by 0.01% its kinetic energy will increase by
Solution:
QUESTION: 10

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: 11

In the following combinations of logic gates, the outputs of A, B and C are respectivley Solution:
QUESTION: 12
Find the maximum velocity for overturn for a car moved on a circular track of radius 100 m. The coefficient of friction between the road and tyre is 0.2
Solution:
QUESTION: 13

An alpha nucleus of energy 1/2 mv2  bombards a heavy nuclear target of charge Ze. Then the distance of closest approach for the alpha nucleus will be proportional to

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): We cannot think of a magnetic configuration with three poles.
Reason(R): A bar magnet does exert a torque on itself due to its own field.
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): Gravitational field intensity at the centre of ring is zero.
Reason(R): Net force at the centre of ring is zero.
Solution:
QUESTION: 16

A disc is of mass M and radius r. The moment of inertia of it about an axis tangential to its edge and in plane of the disc or parallel to its diameter is

Solution:
QUESTION: 17

Helium gas at 27oC has a volume of 8 L. It is suddenly compressed to a volume of 1 L. The final temperature of the gas will be(γ = 5/3 )

Solution:

T1 V1 γ-1 = T2 V2 γ-1
or 300 (8)5/3 - 1 = T2 (1)5/3 - 1
T2 = 300 {(2)3}2/3 = 1200 K
or T2 = 927oC

QUESTION: 18
A tuning fork produces waves in a medium. If the temperature of the medium changes, then which of the following will change
Solution:
QUESTION: 19
Solution:
QUESTION: 20

The radionuclide 56Mn is being produced in a cyclotron at a constant rate P by bombarding a manganese target with deutrons. 56Mn has a half life of 2.5 hours and the target contains large number of only the stable manganese isotope 55Mn. The reaction that produces 56Mn is:

55Mn + d 56Mn+P

After being bombarded for a long time, the activity of 56Mn becomes constant equal to 13.86×1010s−1. (Use ln2 = 0.693; Avogadro number = 6×1023; atomic weight of 56Mn = 56gm/mole)

Q. After a long time bombardment, number of 56Mn nuclei present in the target depends upon
(a) The number of 56Mn nuclei present at the start of the process
(b) Half life of the 56Mn
(c) The constant rate of production P

Solution:
*Answer can only contain numeric values
QUESTION: 21

After five half-lives percentage of original radioactive atoms left is:-

Solution: *Answer can only contain numeric values
QUESTION: 22

In series LR circuit XL = 3R. Now a capacitor with XC = R is added in series. Ratio of new to old power factor is :-

Solution: *Answer can only contain numeric values
QUESTION: 23

In a galvanometer, the deflection becomes one half when the galvanometer is shunted by a 20Ω resistor. The galvanometer resistance is Solution: *Answer can only contain numeric values
QUESTION: 24

If an objects is placed symmetrically between two plane mirrors, inclined at an angle of 72°, then the total number of images formed is :-

Solution:
*Answer can only contain numeric values
QUESTION: 25

A tuning fork gives 4 beats with 50cm length of a sonometer wire. If the length of the wire is shortened by 1cm, the number of beats is still the same. The frequency of the fork (in Hz) is :-

Solution: 