Nuclei — Physics STD 12 Science — Question

The resistance of a wire is   per metre. It is bend in the form of a circle of diameter 2 m. A wire of the same material is connected across its diameter. The total resistance across its diameter AB will be

(a)

(b)

(c) 0.88

(d) 14π

The radius of curvature of the path of the charged particle in a uniform magnetic field is directly proportional to

(a) The charge on the particle	(b) The momentum of the particle
(c) The energy of the particle	(d) The intensity of the field

A strip of copper and another of germanium are cooled from room temperature to 80 K. The resistance of

(a) Each of these increases

(b) Each of these decreases

(c) Copper strip increases and that of germanium decreases

(d) Copper strip decreases and that of germanium increases

In the circuit shown below, the power developed in the 6W resistor is 6 watt. The power in watts developed in the 4W resistor is

(a) 16

(b) 9

(c) 6

(d) 4

A vertical wire carrying a current in the upward direction is placed in horizontal magnetic field directed towards north. The wire will experience a force directed towards

(a) North

(b) South

(c) East

(d) West

For harder X-rays:

1. The wavelength is higher.
2. The intensity is higher.
3. The frequency is higher.
4. The photon energy is higher.

.......... Property develops in comb due to friction.

A voltmeter essentially consists of

(a) A high resistance, in series with a galvanometer

(b) A low resistance, in series with a galvanometer

(c) A high resistance in parallel with a galvanometer

(d) A low resistance in parallel with a galvanometer

Two positive charges of 20 coulomb  and Q coulomb are situated at a distance of 60 cm. The neutral point between them is at a distance of 20 cm from the 20 coulomb charge. Charge Q is

(a) 30 C

(b) 40 C

(c) 60 C

(d) 80 C