Moving Charges and Magnetism — Physics STD 12 Science — Question

 Find equivalent capacitance between A and B

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

Water boils in an electric kettle in 15 minutes after switching on. If the length of the heating wire is decreased to 2/3 of its initial value, then the same amount of water will boil with the same supply voltage in

(a) 15 minutes

(b) 12 minutes

(c) 10 minutes

(d) 8 minutes

The binding energy per nucleon of iron atom is approximately.

A semiconductor device is connected in a series circuit with a battery and a resistance. A current is found to pass through the circuit. If the polarity of the battery is reversed, the current drops to almost zero. The device may be a/ an?

Huygens's concept of secondary wave:

A molecule with a dipole moment p is placed in an electric field of strength E. Initially the dipole is aligned parallel to the field. If the dipole is to be rotated to be anti-parallel to the field, the work required to be done by an external agency is

(a) – 2pE

(b) – pE

(c) pE

(d) 2pE

The dielectric constant k of an insulator cannot be

(a) 3

(b) 6

(c) 8

(d) ∞

A resistor  dissipates the power P when connected to a certain generator. If the resistor  is put in series with , the power dissipated by

(a) Decreases

(b) Increases

(c) Remains the same

(d) Any of the above depending upon the relative values of  and

For right-angled prism, ray- 1 is the incident ray and ray as the emergent ray as shown in the figure. Refractive index of the prism is __________ .