Atoms — Physics STD 12 Science — Question

In a semiconductor diode, the depletion region is removed when:

Light enters at an angle of incidence in a transparent rod of refractive index n. For what value of the refractive index of the material of the rod the light once entered into it will not leave it through its lateral face whatsoever be the value of angle of incidence

(a) n >

(b) n = 1

(c) n = 1.1

(d) n = 1.3

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:

In  solution when electric current equal to 2.5 faraday is passed, the gm equivalent deposited on the cathode is

(a) 1

(b) 1.5

(c) 2

(d) 2.5

The heat developed in an electric wire of resistance R by a current I for a time t is

(a)

(b)

(c)

(d)

Which of the following is an example of a non-ohmic conductor?

The absorption transitions between the first and the fourth energy states of hydrogen atom are 3. The emission transitions between these states will be    

(a) 3

(b) 4

(c) 5

(d) 6

The line on the earth's surface joining the points where the field is horizontal is

(a) Magnetic meridian

(b) Magnetic axis

(c) Magnetic line

(d) Magnetic equator

Which one of the following is inorganic compound semiconductor?

Forty electric bulbs are connected in series across a 220 V supply. After one bulb is fused, the remaining 39 are connected again in series across the same supply. The illumination will be

(a) More with 40 bulbs than with 39	(b) More with 39 bulbs than with 40
(c) Equal in both the cases	(d) In the ratio of