Atoms — Physics STD 12 Science — Question

Two bulbs are in parallel and they together consume 48 W from a battery of 6 V. The resistance of each bulb is

(a) 0.67 Ω

(b) 3.0 Ω

(c) 4.0 Ω

(d) 1.5 Ω

The particle nature of light is not confirmed by:

At a certain place, the horizontal component of earth's magnetic field is  times the vertical component. The angle of dip at that place is

(a) 60°

(b) 45°

(c) 90°

(d) 30°

Assertion  :   Dielectric breakdown occurs under the influence of an intense light beam.

Reason      : Electromagnetic radiations exert pressure.

(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.

_________ Charge is produced by friction.

The ratio of the frequencies of the long wavelength limits of Lyman and Balmer series of hydrogen spectrum is

(a) 27 : 5

(b) 5 : 27

(c) 4 : 1

(d) 1 : 4

The period of the wave will be.

The fusion of light elements take place at about the temperatures of about:

An oil drop having charge 2e is kept stationary between two parallel horizontal plates 2.0 cm apart when a potential difference of 12000 volts is applied between them. If the density of oil is 900 kg/m³, the radius of the drop will be

(a) 2.0

(b) 1.7

(c) 1.4

(d) 1.1

A dip circle is taken to geomagnetic equator. The needle is allowed to move in a vertical plane perpendicular to the mangetic meridian. the needle will stay in: