In a historical experiment to determine Planck’s constant, a metal surface was irradiated with light of different wavelengths. The emitted photoelectron energies were measured by applying a stopping potential. The relevant data for the wavelength ( $λ$ ) of incident light and the corresponding stopping potential $(V_{0})$ are given below:
Given that $c = 3 \times 10^{8} m s^{- 1}$ and $e = 1.6 \times 10^{- 19} C$ , Planck's constant (in units of J s ) found from such an experiment is

Question

In a historical experiment to determine Planck’s constant, a metal surface was irradiated with light of different wavelengths. The emitted photoelectron energies were measured by applying a stopping potential. The relevant data for the wavelength ( $λ$ ) of incident light and the corresponding stopping potential $(V_{0})$ are given below:

Given that $c = 3 \times 10^{8} m s^{- 1}$ and $e = 1.6 \times 10^{- 19} C$ , Planck's constant (in units of J s ) found from such an experiment is

Infinity Learn · Accepted Answer

From $$hv=W+KEmaxhc$$λ$$=W+V0e$$ For λ$$=0.3$$μm:$$hc3$$×$$10$$−$$7=W+2$$×$$1.6$$×$$10$$−$$19$$→(1) For λ$$=0.4$$μm:$$hc4$$×$$10$$−$$7=W+1.6$$×$$10$$−$$19$$→(2)Subtract$$ $$(1)−(2)⇒$$hc13$$−$$14$$×$$107=1.6$$×$$10$$−$$19$$ ⇒$$h=1.6$$×$$12$$×$$10$$−$$263$$×$$108=6.4$$×$$10$$−$$34Js$$

Remember concepts with our Masterclasses.

Ready to Test Your Skills?

free study material