Class 12 Physics

NCERT Exemplar Solutions for CBSE Class 12 Physics, Chapter 6 (from question number 6.1 to 6.6) are given below:

Question 7: A metal plate is getting heated. It can be because

(a) a direct current is passing through the plate

(b) it is placed in a time varying magnetic field

(c) it is placed in a space varying magnetic field, but does not vary with time

(d) a current (either direct or alternating) is passing through the plate

Solution 7: (a), (b), (d)

When current (either direct or alternating) is passed through the plate its temperature will increase. When the same plate is placed in the time varying magnetic field then eddy current will be produced which in turn will produce heat in the metal plate.

NCERT Exemplar Textbook: CBSE Class 12 Physics – All Chapters

Question 8: An emf is produced in a coil, which is not connected to an external voltage source. This can be due to

(a) the coil being in a time varying magnetic field

(b) the coil moving in a time varying magnetic field

(c) the coil moving in a constant magnetic field

(d) the coil is stationary in external spatially varying magnetic field, which does not change with time

Solution 8: (a), (b), (c)

EMF is produced in the coil when magnetic flux associated with it changes. Therefore, options (a), (b) and (c) are correct.

Question 9:

The mutual inductance M₁₂ of coil 1 with respect to coil 2

(a) increases when they are brought nearer

(b) depends on the current passing through the coils

(c) increases when one of them is rotated about an axis

(d) is the same as M₂₁ of coil 2 with respect to coil 1

Solution 9:  (a) (d)

When two coils are brought nearer, then their mutual inductance increases. Also, M₁₂ = M₂₁.

Question 10:

A circular coil expands radially in a region of magnetic field and no electromotive force is produced in the coil. This can be because

(a) the magnetic field is constant

(b) the magnetic field is in the same plane as the circular coil and it may or may not vary

(c) the magnetic field has a perpendicular (to the plane of the coil) component whose magnitude is decreasing suitably

(d) there is a constant magnetic field in the perpendicular (to the plane of the coil) direction

Solution 10: (b), (c)

Electromotive force is not produces in the coil if the magnetic field has a perpendicular (to the plane of the coil) component whose magnitude is decreasing suitably & there is a constant magnetic field in the perpendicular (to the plane of the coil) direction.