41.

If modulation index is 1/2 and power of carrier wave is 2 W. Then what will be the total power in modulated wave?

• 0.5 W

• 1 W

• 0.25 W

• 2.25 W

If velocity of a particle is three times of that of electron and ratio of de Broglie wavelength of particle to that of electron is 1.814 x 10^-4. The particle will be

• Neutron

• Deuteron

• Alpha

• Tritium

In an intrinsic semiconductor band gap is 1.2 eV then ratio of number of charge carriers at 600 K and 300 K is

• 10⁴

• 10⁷

• 10⁵

• 10³

Long distance communication between two point or earth is achieved by

• Space wave communication

• Sky wave communication

• Satellite wave communication

• Line of sight transmission

Polaroid glass is used in sun glasses because

• it reduces the light intensity to half on account of polarisation

• it is fashionable

• it has good colour

• it is cheaper

Which of the following statement is incorrect?

• Neutron is less stable than proton

• Neutron can cause fission in nuclear reactors but proton can not.

• A free proton can emit beta particle.

• A bound proton can emit beta particle.

Electric field at a distance r from infinitely long conducting sheet is proportional to

• r^-1

• r^-2

• r^-3/2

• independent of r

In a Young's double slit experiment the spacing between the slits is 0.3 mm and the screen is kept at a distance of 1.5 m. The second bright fringe is found 6 mm from the central fringe. The wavelength of the light used in the experiment is

• 625 nm

• 600 nm

• 550 nm

• 500 nm

In beta plus decay

• antineutrino is produced with electron

• neutrino is produced with positron

• neutron is produced with electron

• none of these

The frequency of a light wave in a material is 2 × 10¹⁴ Hz and wavelength is 5000 A^o. The refractive index of material will be

• 1.50

• 3.00

• 1.33

• 1.40