Chemistry Class 11 NCERT Solutions: Chapter 2 Structure of Atom Part 16

Q: 52. Following results are observed when sodium metal is irradiated with different wavelengths. Calculate

(a) Threshold wavelength and,

(b) Planck’s constant

Threshold wavelength and planks constant
Threshold wavelength and planks constant

Equation

Equation

Equation

Equation

Equation

Equation

Equation

Equation

(A) Assuming the threshold wavelength to be Equation , the kinetic energy of the radiation is given as:

Equation

Three different equalities can be formed by the given value as:

Equation

Equation

Equation (1)

Similarly,

Equation (2)

Equation (3)

Dividing equation (3) equation (1):

Equation

Equation

Equation

Equation

Equation

Equation

Equation

Equation

Note: part (b) of the question is not done due to the incorrect values of velocity given in the question.

Q: 53. The ejection of the photoelectron from the silver metal in the photoelectric effect experiment can be stopped by applying the voltage of Equation V when the radiation Equation is used. Calculate the work function for silver metal.

Answer:

From the principle of conservation of energy, the energy of an incident photon (E) is equal to the sum of the work function Equation of radiation and its kinetic energy (K.E) i.e.,

Equation

Equation

Energy of incident photon (E) Equation

Where,

C=velocity of radiation

h=Planck’s constant

Equation Wavelength of radiation

Substituting the values in the given expression of E:

Equation

Equation

Equation

Equation

The potential applies to silver metal changes to kinetic energy (K.E) of the photoelectron. Hence,

Equation

Equation

Equation

Equation

Equation

Explore Solutions for Chemistry

Sign In