Electric Charges and Fields — Physics STD 12 Science — Question

The rest energy involved in a mass of one atomic mass unit is _________ eV.

The lead marked with the arrow is the _______.

A charged particle is whirled in a horizontal circle on a frictionless table by attaching it to a string fixed at one point. If a magnetic field is switched on in the vertical direction the tension in the string.

In a cyclotron, the angular frequency of a charged particle is independent of

(a) Mass

(b) Speed

(c) Charge

(d) Magnetic field

At a point 20 cm from the centre of a uniformly charged dielectric sphere of radius 10 cm, the electric field is 100 V/m. The electric field at 3 cm from the centre of the sphere will be

(a) 150 V/m

(b) 125 V/m

(c) 120 V/m

(d) Zero

A dielectric slab of thickness d  is inserted in a parallel plate capacitor whose negative plate is at x = 0 and positive plate is at x = 3d. The slab is equidistant from the plates. The capacitor is given some charge. As one goes from 0 to  3d

(a) The magnitude of the electric field remains the same

(b) The direction of the electric field remains the same

(c) The electric potential increases continuously

(d) b, c

A photo cell is a device which:

Identify the dimensional formula of electric current.

Doppler's effect in sound in addition to relative velocity between source and observer, also depends while source and observer or both are moving. Doppler effect in light depend only on the relative velocity of source and observer. The reason of this is

(a) Einstein mass - energy relation	(b) Einstein theory of relativity
(c) Photoelectric effect	(d) None of these

A photon will have less energy, if its: