Alternating Current — Physics STD 12 Science — Question

In annihilation process, in which an electron and a positron transform into two gamma rays, which property of electric charge is displayed?

Name the unit of electrical potential:

The magnetic susceptibility is negative for:

In the arrangement shown in given Figure, there are two coils wound on a non-conducting cylindrical rod. Initially the key is not inserted. Then the key is inserted and later removed. Then,

Assertion  :   For a perfectly diamagnetic substance permeability is always one.

Reason       : The ability of a material of permit the passage of magnetic lines of force through it is called magnetic permeability.

(a) If both assertion and reason are true and the reason is the correct explanation of the assertion.

(b) If both assertion and reason are true but reason is not the correct explanation of the assertion.

(c) If assertion is true but reason is false.

(d) If assertion is false but reason is true.

Kirchhoff's first law i.e.   at a junction is based on the law of conservation of

(a) Charge

(b) Energy

(c) Momentum

(d) Angular momentum

The magnitude of the earth’s magnetic field at a place is  and the angle of dip is δ. A horizontal conductor of length l lying along the magnetic north-south moves eastwards with a velocity v. The emf induced across the conductor is

(a) Zero

(b)

(c)

(d)

A point charge q is rotated along a circle in the electric field generated by another point charge Q. The work done by the electric field on the roatating charge in one complete revolution is:

1. Zero.
2. Positive.
3. Negative.
4. Zero if the charge Q is at the centre and nonzero otherwise.

 ————— gives the information on field strength, direction, and nature of the charge.