Electric Charges and Fields — Physics STD 12 Science — Question

An infinitely long straight conductor is bent into the shape as shown in the figure. It carries a current of i ampere and the radius of the circular loop is r metre. Then the magnetic induction at its centre will be

(a)

(b)

(c) Zero

(d) Infinite

A particle is projected in a plane perpendicular to a uniform magnetic field. The area bounded by the path described by the particle is proportional to:

If the voltage of X-ray tube is doubled, the intensity of X-rays will become

(a) Half

(b) Unchanged

(c) Double

(d) Four times

In an electroplating experiment, m gm of silver is deposited when 4 ampere of current flows for 2 minute. The amount (in gm) of silver deposited by 6 ampere of current for 40 second will be

(a) 4 m

(b) m/2

(c) m/4

(d) 2 m

Reciprocal of Impedance is:

The minimum energy required for the electron emission from the metal surface can be supplied to the free electrons by which of the following physical processes?

The electron in a hydrogen atom makes a transition , where   and  are the principal quantum numbers of the two states. Assume the Bohr model to be valid. The time period of the electron in the initial state is eight times that in the final state. The possible values of n₁ and n₂ are

(a)

(b)

(c)

(d)

Suppose a planet goes around Sun with a linear speed twice as fast that of earth. What will be it's orbit size as compared to that of earth ? (Radius of earth = R)

(a) R / 4

(b) R / 2

(c) R

(d) 2R

A small bar magnet A oscillates in a horizontal plane with a period T at a place where the angle of dip is 60^o. When the same needle is made to oscillate in a vertical plane coinciding with the magnetic meridian, its period will be

(a)

(b) T

(c)

(d) 2T

Magnetic dipole moment is a vector quantity directed from: