Semiconductor Electronic: Material, Devices And Simple Circuits — Physics STD 12 Science — Question

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

Two coherent sources of different intensities send waves which interfere. The ratio of maximum intensity to the minimum intensity is 25. The intensities of the sources are in the ratio:

1. 25 : 1
2. 5 : 1
3. 9 : 4
4. 625 : 1

The energy of a photon of a characteristic X-ray from a Coolidge tube comes from:

Four charges +Q, -Q, +Q, -Q  are placed at the corners of a square taken in order. At the centre of the square

(a) E = 0, V = 0

(b) E = 0, V ≠ 0

(c) E ≠ 0, V = 0

(d) E = 0, V ≠ 0

Electric potential is given by T, hen electric force acting on 2C  point charge placed on origin will be

(a) 2N

(b) 6N

(c) 8N

(d) 20 N

For a thermocouple, the neutral temperature is 270℃ and the temperature of its cold junction is 20℃. If there is no deflection in the galvanometer, the temperature of the hot junction should be

(a) 210 ℃

(b) 540 ℃

(c) 520 ℃

(d) 209 ℃

Two bullets are fired simultaneously, horizontally and with different speeds from the same place. Which bullet will hit the ground first?

1. The faster one.
2. The slower one.
3. Both will reach simultaneously.
4. Depends on the masses.

The power factor of L-R circuit is :

What inferences were drawn from Oersteds experiment?