Semiconductor Electronics: Materials, Devices and Simple Circuits — Physics STD 12 Science — Question

A radio transmitter radiates 1 kW power at a wavelength 198.6 metres. How many photons does it emit per second

(a)

(b)

(c)

(d)

Frequency and potential difference of AC sent to homes in India is:

Which of the following is a natural magnet?

When electron changes its orbit from outer to inner energy is:

Evidence for the wave nature of light cannot be obtained from

(a) Reflection

(b) Doppler effect

(c) Interference

(d) Diffraction

In a PN-junction

(a) P and N both are at same potential

(b) High potential at N side and low potential at P side

(c) High potential at P side and low potential at N side

(d) Low potential at N side and zero potential at P side

S.I. unit of electric depole moment is :

The focal length of the field lens (which is an achromatic combination of two lenses) of telescope is 90 cm. The dispersive powers of the two lenses in the combination are 0.024 and 0.036. The focal lengths of two lenses are

(a) 30 cm and 60 cm	(b) 30 cm and – 45 cm
(c) 45 cm and 90 cm	(d) 15 cm and 45 cm

In Young’s experiment, monochromatic light is used to illuminate the two slits A and B. Interference fringes are observed on a screen placed in front of the slits. Now if a thin glass plate is placed normally in the path of the beam coming from the slit

 

(a) The fringes will disappear

(b) The fringe width will increase

(c) The fringe width will increase

(d) There will be no change in the fringe width but the pattern shifts

If E  is the electric field intensity of an electrostatic field, then the electrostatic energy density is proportional to

(a) E

(b)

(c)

(d)