Magnetism And Matter — Physics STD 12 Science — Question

A plane mirror is approaching you at a speed of 10 cm/sec You can see your image in it. At what speed will your image approach you

(a) 10 cm/sec

(b) 5 cm/sec

(c) 20 cm/sec

(d) 15 cm/sec

There is some liquid in a closed bottle. The amount of liquid is continuously decreasing. The vapour in the remaining part:

1. Must be saturated.
2. Must be unsaturated.
3. May be saturated.
4. There will be no vapour.

Which source is associated with a line emission spectrum

(a) Electric fire

(b) Neon street sign

(c) Red traffic light

(d) Sun

Assertion : Red shift confirms that the universe is expanding

Reason     :  Wavelength of red light is maximum in the visible region

(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 refractive index of flint glass for blue F line is 1.6333 and red C line is 1.6161. If the refractive index for yellow D line is 1.622, the dispersive power of the glass is

(a) 0.0276

(b) 0.276

(c) 2.76

(d) 0.106

In semiconductors, at room temperature:

A converging lens is used to form an image on a screen. When upper half of the lens is covered by an opaque screen

(a) Half the image will disappear

(b) Complete image will be formed of same intensity

(c) Half image will be formed of same intensity

(d) Complete image will be formed of decreased intensity