HSC Science Class 12 - Tamil Nadu Board of Secondary Education Question Bank Solutions

What is a surface barrier?

Mention the two features of x-ray spectra, not explained by classical electromagnetic theory.

Briefly discuss the observations of Hertz, Hallwachs and Lenard.

Explain the effect of potential difference on photoelectric current.

Explain how frequency of incident light varies with stopping potential.

List out the laws of photoelectric effect.

Explain the quantum concept of light.

Obtain Einstein’s photoelectric equation with the necessary explanation.

Explain experimentally observed facts of the photoelectric effect with the help of Einstein’s explanation.

Give the construction and working of photo emissive cell.

List out the characteristics of photons.

Give the applications photocell.

How many photons per second emanate from a 50 mW laser of 640 nm?

Calculate the maximum kinetic energy and maximum velocity of the photoelectrons emitted when the stopping potential is 81 V for the photoelectric emission experiment.

Calculate the energies of the photons associated with the following radiation:

1. violet light of 413 nm
2. X-rays of 0.1 nm
3. radio waves of 10 m

How many photons of frequency 10¹⁴ Hz will make up 19.86 J of energy?

When a light of frequency 9 × 10¹⁴ Hz is incident on a metal surface, photoelectrons are emitted with a maximum speed of 8 × 10⁵ ms⁻¹. Determine the threshold frequency of the surface.

When a 6000 Å light falls on the cathode of a photo cell, photoemission takes place. If a potential of 0.8 V is required to stop emission of electron, then determine the

1. frequency of the light
2. energy of the incident photon
3. work function of the cathode material
4. threshold frequency and
5. net energy of the electron after it leaves the surface.

A 3310 Å photon liberates an electron from a material with energy 3 × 10⁻¹⁹ J while another 5000 Å photon ejects an electron with energy 0.972 × 10⁻¹⁹ J from the same material. Determine the value of Planck’s constant and the threshold wavelength of the material.

At the given point of time, the earth receives energy from the sun at 4 cal cm^–2 min^–1. Determine the number of photons received on the surface of the Earth per cm2 per minute. (Given: Mean wavelength of sunlight = 5500 Å)