Ray Optics and Optical Instruments — Physics STD 12 Science — Question

Identify the combination which is not a series connection.

In  solution when electric current equal to 2.5 faraday is passed, the gm equivalent deposited on the cathode is

(a) 1

(b) 1.5

(c) 2

(d) 2.5

A small source of sound moves on a circle as shown-in figure and an observer is sitting at 0. Let v₁, v₂, v₃ be the frequencies heard when the source is at A, B and C respectively.

1. v₁ > v₂ > v₃

2. v₁ = v₂ > v₃

3. v₂ > v₃ > v₁

4. v₁ > v₂ > v₂.

Huygens principle of secondary waves:

The capacity of a condenser is 4   farad and its potential is 100 valts. The energy released on discharging it fully will be

(a) 0.02 Joule

(b) 0.04 Joule

(c) 0.025 Joule

(d) 0.05 Joule

The plate current in a diode is zero. It is possible that:

1. The plate voltage is zero.
2. The plate voltage is slightly negative.
3. The plate voltage is slightly positive.
4. The temperature of the filament is low.

Two charges  and  are placed in vacuum at a distance d  and the force acting between them is F. If a medium of dielectric constant 4 is introduced around them, the force now will be

(a) 4F

(b) 2F

(c)

(d)

The permanent magnetic moment of the atoms of a material is zero. The material:

Assertion   :   Bending a wire does not effect electrical resistance.

Reason       : Resistance of wire is proportional to resistivity of material.

(a) If both assertion and reason are true and the reason is the correct explanation of the assertion.

(b) If both assertion and reason are true but reason is not the correct explanation of the assertion.

(c) If assertion is true but reason is false.

(d) If the assertion and reason both are false.