Planks Constant Questions and Answers for Viva

Answer-1: Planck's Constant represents the Photon Potential Energy. Planck's Energy, E= is the key to Planck's constant.

Answer-2: Photo electric effect is a process where electron are ejected from a surface by the action of light (Electromagnetic Radiation)

Answer-3: The unit is Joule-second.

Answer-4: A photon is characterized by either a wavelength, denoted by λ or equivalently an energy, denoted by E. There is an inverse relationship between the energy of a photon (E) and the wavelength of the light (λ) given by the equation:
E = hc/λ

Answer-5: As the frequency of electromagnetic radiation increases, the energy of each photon increases. These quantities are directly proportional; within a constant (Planck's constant).

Answer-6: Laws of Photoelectric Effect:

1. For a given substance there is certain minimum frequency of light called threshold frequency ?0bvelow which no photoelectric emission takes place whatever be the intensity of light.
2. The number of photoelectrons emitted per second by a substance is directly proportional to the intensity of the incident photon beam.
3. The maximum kinetic energy of the emitted photoelectrons is directly proportional to the frequency of incident photon beam and is independent of the intensity of the light.
4. The process of photoelectric effect is instantaneous i.e. as soon as the light whose frequency greater than threshold frequency falls on metal surface electrons are emitted [within 10^-9s]

Answer-7: Light of shorter wavelength is more effective in producing photo- electrons than light of longer wavelength.

Answer-8: It is the constant of proportionality relating the energy of a photon to the frequency of that photon. Its value is approximately 6.626 ? 10^-34 joule-second. Its symbol is h.

Answer-9: Planck's constant is important for several reasons: it defines the quanta (minimum amount) for the energy of light and therefore also the energies of electrons in atoms. It also factors into something called the Uncertainty Principle.

Answer-10: Photoelectrons are emitted from a metallic surface only when the incident light has more than a certain minimum frequency.