Electric Charges and Fields — Physics STD 12 Science — Question

Assertion   :  Electric appliances with metallic body have three connections, whereas an electric bulb has a two pin connection.

Reason       : Three pin connections reduce heating of connecting wires.

(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.

In the diagram shown if a bar magnet is moved along the common axis of two single turn coils A and B in the direction of arrow then-

X-ray incident on a material:

A convex mirror has a focal length f. A real object is placed at a distance f in front of it from the pole produces an image at

(a) Infinity

(b) f

(c) f/2

(d) 2f

Chadwick was awarded the 1935 nobel prize in physics for his discovery of the:

From the graph between current I and voltage V shown below, identify the portion corresponding to negative resistance

(a) AB

(b) BC

(c) CD

(d) DE

In a situation the contact force by a rough horizontal surface on a body placed on it has constant magnitude. If the angle between this force and the vertical is decreased, the frictional force between the surface and the body will:

1. Increase.
2. Decrease.
3. Remain the saint.
4. May increase or decrease.

In photoelectric effect, the K.E. of electrons emitted from the metal surface depends upon

(a) Intensity of light	(b) Frequency of incident light
(c) Velocity of incident light	(d) Both intensity and velocity of light

Give the unit of work function.

The current through a 4.6 H inductor is shown in the following graph. The induced emf during the time interval t = 5 milli-sec to 6 milli-sec will be

(a) 103 V

(b) – 23 × 103 V

(c) 23 × 103 V

(d) Zero