In This Post we are providing Chapter-4 Moving Charges and Magnetism NCERT MCQ for Class 12 Physics which will be beneficial for students. These solutions are updated according to 2021-22 syllabus. These MCQS can be really helpful in the preparation of Board exams and will provide you with a brief knowledge of the chapter.
NCERT MCQ ON MOVING CHARGES AND MAGNETISM
Question 1.
A charge moving with a velocity v in X-direction is subjected to a field of magnetic induction in the negative X direction. As a result, the charge will:
(a) remain undefeated
(b) retard along X-axis
(c) start moving in a circular path in YZ plane.
(d) move along a helical path around X-axis.
Answer: (a) remain undefeated
Question 2.
Two thin long parallel wires separated by a distance r are carrying a current I amp. each. The magnitude of the force per unit length applied by one wire on the other is:
(a) µ0I2r2
(b) µ0I22πr
(c) µ0I2πr
(d) µ0I24πr
Answer: (b) µ0I22πr
Question 3.
A wire is placed parallel to the lines of force in a magnetic field and a current flows in the wire, then:
(a) The wire will experience a force in the direction of the magnetic field.
(b) The wire will experience a force in a direction opposite to the magnetic field.
(c) It will experience a force in a direction perpendicular to the lines of force.
(d) Tire wire will not experience a force at all.
Answer: (d) Tire wire will not experience a force at all.
Question 4.
In order to increase the sensitivity of a moving coil galvanometer,
(a) the suspension wire should be made stiff.
(b) the arc of the coil should be reduced.
(c) the magnetic field should be increased.
(d) the number of turns in the coil should be reduced.
Answer: (a) the suspension wire should be made stiff.
Question 5.
Two particles A and B having equal charges after being accelerated through the same potential difference enter a region of uniform magnetic field and describe circular path of radii R1 and R2 respectively. The ratio of the masses of A to B is:
(a) (R1R2)1/2
(b) (R2R1)
(c) (R1R2)²
(d) R1R2
Answer: (c) (R1R2)²
Question 6.
When a charged particle moves perpendicular to a uniform magnetic field, its:
(a) Energy and momentum both change.
(b) Energy and momentum both don’t change.
(c) Energy changes but momentum remains unchanged.
(d) Momentum changes but energy remains unchanged.
Answer: (d) Momentum changes but energy remains unchanged.
Question 7.
The force on a current carrying conductor in a magnetic field is maximum, when angle between the length of the conductor and the magnetic field is:
(a) π2
(b) π4
(c) π
(d) zero
Answer: (a) π2
Question 8.
What happens between the two streams of electrons moving parallel to each other in the same direction:
(a) attract each other
(b) cross the electric and magnetic field of each other.
(c) repel each other.
(d) none of these
Answer: (c) repel each other.
Question 9.
Magnetic field is not associated with:
(a) a charge in uniform motion.
(b) a decelerated charge.
(c) an accelerated charge.
(d) a stationary change.
Answer: (d) a stationary change.
Question 10.
A magnetic needle is kept in a non-uniform magnetic field. It experiences:
(a) a force and torque.
(b) a force but not a torque.
(c) a torque but not a force.
(d) neither a force nor a torque.
Answer: (a) a force and torque.
Question 11.
A proton and an electron enter a region in which a magnetic field is suddenly switched on. The forces experienced by them are:
(a) equal and opposite.
(b) different in magnitude but in same direction.
(c) in the ratio of 1840.
(d) same in magnitude and direction.
Answer: (a) equal and opposite.
Question 12.
Two protons move parallel to each other with equal speeds 3 × 102 m/s. The ratio of magnetic and electrical forces between them is:
(a) 10-6
(b) 10-3
(c) 10-9
(d) 1
Answer: (a) 10-6
Question 13.
A proton and an a particle enter in a uniform magnetic field with the same velocity. The period of rotation of the α-particle will be:
(a) four times that of the proton.
(b) three times that of the proton.
(c) two times that of the proton.
(d) same as that of the proton.
Answer: (c) two times that of the proton.
Question 14.
The magnetic field at the center of a square loop of side a carrying a current I is:
(a) µ04π √2 1a
µ04π 421√4π
(c) µ04π 8√2 1a
(d) none
Answer: (c) µ04π 8√2 1a
Question 15.
A circular of radius R carries a current I. The magnetic field at its centre is B. At what distance from the centre on the axis of the coil, the magnetic field will be B8?
(a) √2R
(b) √3R
(c) 2R
(d) 3R
Answer: (b) √3R
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