Electric Charges and Fields — Physics STD 12 Science — Question

If resistance of voltmeter is 10000 W and resistance of ammeter is 2 W then find R when voltmeter reads 12V and ammeter reads 0.1 A

(a) 118 W

(b) 120 W

(c) 124 W

(d) 114W

Figure shows a charge q placed at the centre of a hemisphere. A second charge Q is placed at one of the positions A, B, C and D. In which position(s) of this second charge, the flux of the electric field through the hemisphere remains unchanged?

1. A
2. B
3. C
4. D

Assertion  :   The presence of water molecules makes separation of ions easier in electrolyte.  

Reason    : The presence of water molecules in electrolyte decreases the resistance of electrolyte.

(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 phase difference between incident wave and reflected wave is 180° when light ray

(a) Enters into glass from air	(b) Enters into air from glass
(c) Enters into glass from diamond	(d)  Enters into water from glass

If frequency of the incident photon on the metal surface is made double, then kinetic energy of the emitted photoelectron will become :

Current density of a conductor is

A capacitor of capacity  is charged to the potential of . On disconnecting with the battery, it is connected with a capacitor of capacity   as shown in the adjoining figure. The ratio of energies before and after the connection of switch  S will be

(a) (

(b)

(c)

(d)

10 C charge is passing through any point in electric circuit in 0.5 second. The magnitude of electric current in the circuit in amperes is:

The number of revolutions per second made by an electron in the first Bohr orbit of hydrogen atom is of the order of 3

(a)

(b)

(c)

(d)