Electrostatic Potential and Capacitance — Physics STD 12 Science — Question

Figure shows the electric lines of force emerging from a charged body. If the electric field at A and B are   and   respectively and if the displacement between A and B is r then

(a)

(b)

(c)

(d)

Assertion  :   Semiconductors do not Obey's Ohm's law. 

Reason     : Current is determined by the rate of flow of charge carriers.

(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 assertion is false but reason is true.

The desirable properties for making permanent magnets are:

A 100 mH coil carries a current of 1 ampere. Energy stored in its magnetic field is

(a) 0.5 J

(b) 1 J

(c) 0.05 J

(d) 0.1 J

Assertion   :   Charge is invariant.

Reason      : Charge does not depends on speed of frame of reference.

(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.

The value of current obtained in a moving coil galvanometer is proportional to :

In Millikan oil drop experiment, a charged drop of mass 1.8   is stationary between its plates. The distance between its plates is 0.90 cm and potential difference is 2.0 kilo volts. The number of electrons on the drop is

(a) 500

(b) 50

(c) 5

(d) 0

The energy stored per unit volume of a space is called as:

A heavy nucleus at rest breaks into two fragments which fly off with velocities in the ratio 8 : 1. The ratio of radii of the fragments is

(a) 1 : 2

(b) 1 : 4

(c) 4 : 1

(d) 2 : 1

A charge q is at the center of the circle ABCDE. Which among the following is true if the charge is taken from A to B, C, D, and E?