Magnetism And Matter — Physics STD 12 Science — Question

The capacitance of a spherical condenser is 1μF. If the spacing between the two spheres is 1mm, then the radius of the outer sphere is(a) 30 cm(b) 6 m(c) 5 cm  (d) 3 m

Assertion :   At 0 K Germanium is a superconductor. 
Reason    :    At 0 K Germanium offers zero resistance.(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 the assertion and reason both are false.

Which of the following quantities do not depend on the choice of zero potential or zero potential energy?

A conducting loop is placed in a uniform magnetic field with its plane perpendicular to the field. An emf is induced in the loop if:

1. It is translated.
2. It is rotated about its axis.
3. It is rotated about a diameter.
4. It is deformed.

The frequency of A.C mains in India is.

If flux of the electric field through a closed surface is zero:

1. The electric field must be zero everywhere on the surface.
2. The electric field may be zero everywhere in the surface.
3. The charge inside the surface must be zero.
4. The charge in the vicinity of the surface must be zero.

A piece of wire of resistance 4 ohms is bent through 180°  at its mid point and the two halves are twisted together, then the resistance is(a) 8 ohms(b) 1 ohm(c) 2 ohms(d) 5 ohms