Dual Nature of Radiation and Matter — Physics STD 12 Science — Question

Which of the nine planets is nearest to sun

(a) Venus

(b) Mercury

(c) Mars

(d) Jupiter

A heater of 220 V heats a volume of water in 5 minute time. A heater of 110 V heats the same volume of water in

(a) 5 minutes

(b) 8 minutes

(c) 10 minutes

(d) 20 minutes

A uniform spherical shell gradually shrinks maintaining its shape. The gravitational potential at the centre:

1. Increases.
2. Decreases.
3. Remains constant.
4. Oscillates.

From a newly formed radioactive substance (Half life 2 hours), the intensity of radiation is 64 times the permissible safe level. The minimum time after which work can be done safely from this source is

(a) 6 hours

(b) 12 hours

(c) 24 hours

(d) 128 hours

If   what is the temperature of inversion

(a) -

(b) +

(c) -

(d) +

α - particles of energy 400 KeV are bombarded on nucleus of  . In scattering of α - particles, its minimum distance from nucleus will be

(a) 0.59 nm

(b) 0.59 Å

(c) 5.9 pm

(d) 0.59 pm

The magnetic flux linked with a vector area   in a uniform magnetic field  is

(a)

(b) AB

(c)

(d)

Assertion  :  In transistor common emitter mode as an amplifier is preferred over common base mode.

Reason     : In common emitter mode the input signal is connected in series with the voltage applied to the base emitter function.

(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.

Two parallel pillars are 11 km away from an observer. The minimum distance between the pillars so that they can be seen separately will be

(a) 3.2 m

(b) 20.8 m

(c) 91.5 m

(d) 183 m

Biot-Savart law indicates that the moving electrons (velocity v) produce a magnetic field B such that: