An electron in the hydrogen atom jumps from excited state n to the ground state. The wavlength so emitted illuminates a photo -sensitive material having work function 2.75 eV. If the stopping potential of the photo-electron is 10 V, the value of n is 

• 3

• 4

• 5

• 5

Out of the following which one is not a possible energy for a photon to be emitted by hydrogen atom according to Bohr's atomic model?

• 1.9 eV

• 11.1 eV

• 13.6 eV

• 13.6 eV

A source S₁ is producing, 10¹⁵ photons of wavelength 500 A. Another source S₂ is producing 1.02 x 10¹⁵ photons per second of wavelength 5100 A. Then, power of S₂) (power of S₁) is equal to

• 1.00

• 1.02

• 1.04 A

• 1.04 A

When monochromatic radiation of intensity I falls on a metal surface, the number of photoelectrons and their maximum kinetic energy and N and T respectively. If the intensity of radiation is 2I, the number of emitted electrons and their maximum kinetic energy are respectively

• N and 2T

• 2N and T

• 2N and 2T

• 2N and 2T

The mean free path of electrons in a metal is 4 x 10^-8 m. The electric field which can give on an average 2 eV energy to an electron in the metal will be in unit of V m^-1

• 8 x 10⁷

• 5 x 10^-11

• 8 x 10^-11

• 8 x 10^-11

The number  of photoelectrons emitted from light of a frequency v (higher than the threshold frequency v_o) is proportional to 

• v-v_o

• threshold frequency (v_o)

• the intensity of light

• the intensity of light

Monochromatic light of wavelength 667 nm is produced by a helium-neon laser. The power emitted is 9 mW. The number of photons arriving per second on the average at a target irradiated by this beam is 

• 9 x 10¹⁷

• 3 x 10¹⁶

• 9 x 10¹⁵

• 9 x 10¹⁵

The figure shows a plot of photocurrent versus anode potential for a photosensitive surface for three different radiations. Which one of the following is a correct statement?

• Curves a and b represent incident radiations of different frequencies and different intesities

• Curves a and b represent incident radiations of same frequency but of different intesities

• Curves b and c represent incident radiations of different frequencies and different intensities

• Curves b and c represent incident radiations of different frequencies and different intensities

89.

The work function of a surface of a photosensitive material is 6.2 eV. The wavelength of the incident radiation for which the stopping potential is 5 V lies in the 

• ultraviolet region

• visible region

• infrared region

• infrared region

The ground state energy of hydrogen atom is -13.6 eV. When its electron is in the first excited state, its excitation energy is

• 3.4 eV

• 6.8 eV

• 10.2 eV

• zero