Nuclei — Physics STD 12 Science — Question

As in figure shown, if a capacitor C is charged by connecting it with resistance R, then energy is given by the battery will be

(a)

(b) More than

(c) Less than

(d) Zero

A diode, a resistor and a 50Hz AC source are connected in series. The number of current pulses per second through the resistor is:

1. 25
2. 50
3. 100
4. 200

The half life period of radium is 1600 years. The fraction of a sample of radium that would remain after 6400 years is

(a)

(b)

(c)

(d)

Ratio between total intensity of magnetic field at equator to poles is

(a) 1 : 1

(b) 1 : 2

(c) 2 : 1

(d) 1 : 4

Assertion :   If a point charge q is placed in front of an infinite grounded conducting plane surface, the point charge will experience a force.

Reason     : This force is due to the induced charge on the conducting surface which is at zero potential.

(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.

Heavy water is used as moderator in a nuclear reactor. The function of the moderator is

(a) To control the energy released in the reactor

(b) To absorb neutrons and stop chain reaction

(c) To cool the reactor faster

(d) To slow down the neutrons to thermal energies

The excess pressure inside a soap bubble is twice the excess pressure inside a second soap bubble. The volume of the first bubble is n times the volume of the second where n is:

1. 4
2. 2
3. 1
4. 0.125.

A circular loop of radius 0.0157m carries a current of 2.0 amp. The magnetic field at the centre of the loop is (

(a) 1.57	(b) 8.0
(c) 2.5	(d)  3.14

The amount of charge required to liberate 9 gm of aluminium (atomic weight = 27 and  valency = 3) in the process of electrolysis is (Faraday's number = 96500 coulombs/gm equivalent)

(a) 321660 coulombs

(b) 69500 coulombs

(c) 289500 coulombs

(d) 96500 coulombs

Figure shows a horizontal solenoid connected to a battery and a switch. A copper ring is placed on a frictionless track, the axis of the ring being along the axis of the solenoid. As the switch is closed, the ring will:

1. Remain stationary.
2. Move towards the solenoid.
3. Move away from the solenoid.
4. Move towards the solenoid or away from it depending on which terminal (positive or negative) of the battery is connected to the left end of the solenoid.