Optical Instruments — Physics STD 12 Science — Question

A point source of light is placed in front of a plane mirror:

1. All the reflected rays meet at a point when produced backward.
2. Only the reflected rays close to the normal meet at a point when produced backward.
3. Only the reflected rays making a small angle with the mirror, meet at a point when produced backward.
4. Light of different colours make different images.

The process on an ideal gas, shown in figure. is:

1. Isothermal.
2. Isobaric.
3. Isochoric.
4. None of these.

A radioactive sample at any instant has its disintegration rate 5000 disintegration per minute. After 5 minutes, the rate is 1250 disintegrations per minute. Then, the decay constant (per minute) is

(a) 0.8 In 2

(b) 0.4 In 2

(c) 0.2 In 2

(d) 0.1 In 2

Which of the following is/are optoelectronic devices?

A cell of internal resistance r is connected to an external resistance R. The current will be maximum in R, if:

Energy of electrons can be increased by allowing them

(a) To fall through electric potential	(b) To move in high magnetic field
(c) To fall from great heights	(d) To pass through lead blocks

Under what condition the force acting on the charge particle moving in the magnetic field maximum?

The angle of dip is the angle

(a) Between the vertical component of earth's magnetic field and magnetic meridian

(b) Between the vertical component of earth's magnetic field and geographical meridian

(c) Between the earth's magnetic field direction and horizontal direction

(d) Between the magnetic meridian and the geographical meridian

An ammeter of 100 W resistance gives full deflection for the current of 10^–5 amp.  Now the shunt resistance required to convert it into ammeter of 1 amp. range, will be

(a)  W

(b)  W

(c)  W

(d)  W