Nuclei — Physics STD 12 Science — Question

NPN transistor are preferred to PNP transistor because they have

(a) Low cost

(b) Low dissipation energy

(c) Capability of handing large power

(d) Electrons having high mobility than holes

If the rotational velocity of dynamo armature is doubled, then induced emf will become:

An electron (charge = 1.6 ) is accelerated through a potential of 100,000 V. The energy acquired by the electron is

(a) 1.6

(b) 1.6

(c) 0.53

(d) 1.6

Charge on α -particle is

(a)

(b) 1.6

(c) 3.2

(d) 6.4

Point A is at a lower electrical potential than point B. An electron between them on the line joining them will:

Mark the correct statements for a particle going on a straight line:

1. If the velocity and acceleration have opposite sign, the object is slowing down.
2. If the position and velocity have opposite sign, the particle is moving towards the origin.
3. If the velocity is zero at an instant, the acceleration should also be zero at that instant.
4. If the velocity is zero for a time interval, the acceleration is zero at any instant within the time interval.

Two streams of protons move parallel to each other in the same direction. They will:

It is not convenient to use a spherical Gaussian surface to find the electric field due to an electric dipole using Gauss’s theorem because

(a) Gauss’s law fails in this case

(b) This problem does not have spherical symmetry

(c) Coulomb’s law is more fundamental than Gauss’s law

(d) Spherical Gaussian surface will alter the dipole moment