Alternating Current — Physics STD 12 Science — Question

Four charges are kept at the corner points of a square. The net force on a charge kept at the center of the square is _________?

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

A bar magnet is situated on a table along east-west direction in the magnetic field of earth. The number of neutral points, where the magnetic field is zero, are(a) 2(b) 0(c) 1(d) 4

An electromagnetic wave can be produced when the charge is

All particles of a wave front vibrate:

What happens to the capacitance when a dielectric material is inserted between the plates of a parallel plate capacitor?

Assertion   :   A metallic shield in form of a hollow shell may be built to block an electric field.
Reason       : In a hollow spherical shield, the electric field inside it is zero at every point. (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.

Essential difference between electrostatic shielding by a conducting shell and magnetostatic shielding is due to:

A radioactive substance emits(a) a-rays(b) b-rays(c) g-rays(d) All of these