Atoms — Physics STD 12 Science — Question

In an interference experiment, the spacing between successive maxima or minima is  (Where the symbols have their usual meanings)

(a)

(b)

(c)

(d)

A 20cm long capillary tube is dipped in water. The water rises up to 8cm. If the entire arrangement is put in a freely falling elevator, the length of water column in the capillary tube will be:

1. 8cm
2. 6cm
3. 10cm
4. 20cm

Cathode rays consist of

(a) Photons

(b) Electrons

(c) Protons

(d) α -particles

Optical fibres are related with

(a) Communication

(b) Light

(c) Computer

(d) None of these

If a power of 100 W is being supplied across a potential difference of 200 V, current flowing is

(a) 2 A

(b) 0.5 A

(c) 1 A

(d) 20 A

A millivoltmeter is connected in parallel to an axle of the train running with a speed of 180km/ hour. If the vertical component of earth's magnetic field is 0.2 × 10^-4Wb/ m² and the distance between the rails is 1m, then the reading of voltmeter will be:

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 number of revolutions per second made by an electron in the first Bohr orbit of hydrogen atom is of the order of 3

(a)

(b)

(c)

(d)

The angle of polarisation for any medium is 60^o, what will be critical angle for this

(a)

(b)

(c)

(d)

The lowest frequency of light that will cause the emission of photoelectrons from the surface of a metal (for which work function is 1.65 eV) will be

(a) 4

(b) 4

(c) 4

(d) 4