AP EAMCET2013PhysicsDual Nature of Matter
Initially a photon of wavelength ₁ falls on photocathode and emits an electron of maximum energy E₁ . If the wavelength of the incident photon is changed to ₂ , the maximum energy of the electron emitted becomes E₂ . Then value of h c ( h= Planck's constant, c= velocity of light) is
Options
- Ah c= (E₁+E₂ ) ₁ ₂ ₂- ₁
- Bh c= E₁-E₂ ₂- ₁ ( ₁ ₂ )
- Ch c= (E₁-E₂ ) ( ₂- ₁ ) ₁ ₂
- Dh c= ₂- ₁ ₁ ₂ E₂ E₁
Correct answer
B. h c= E₁-E₂ ₂- ₁ ( ₁ ₂ )
Step-by-step solution
From equation of photoelectric effect, we have aligned & E₁= h c ₁ -W & E₂= h c ₂ -W aligned where, W is work function. aligned & E₁+W= h c ₁ & E₂+W= h c ₂ aligned From Eq. (iv) W= h c ₂ -E₂, Putting this value in Eq. (iii), we have aligned & E₁+ h c ₁ -E₂- h c ₁ & E₁-E₂=h c ( 1 ₁ - 1 ₂ ) & E₁-E₂=h c ( ₂- ₁ ₁ ₂ ) h c= & (E₁-E₂ ) ₁ ₂ ( ₂- ₁ ) aligned