Silver has a work function of 4.7 eV. When ultraviolet light of wavelength 100 nm is incident upon it, a potential of 7.7 volt is required to stop the photoelectrons from reaching the collector plate. Find the potential (in volt) required to stop photo electrons when light of wavelength 200 nm is

Question

Silver has a work function of 4.7 eV. When ultraviolet light of wavelength 100 nm is incident upon it, a potential of 7.7 volt is required to stop the photoelectrons from reaching the collector plate. Find the potential (in volt) required to stop photo electrons when light of wavelength 200 nm is (A)  (B)  (C)  (D)

Tardigrade Admin · Accepted Answer

Given φ=4.7 eV for λ=100 nm , V s =7.7 volt for λ=200 nm V s =? eV s =( ch /λ)-φ =(3 × 108 × 6.62 × 10-34/2 × 10-7 × 1.6 × 10-19)-4.7 =6.2-4.7=1.5 V ⇒ V s =1.5 volt

Q. Silver has a work function of 4.7eV. When ultraviolet light of wavelength 100nm is incident upon it, a potential of 7.7 volt is required to stop the photoelectrons from reaching the collector plate. Find the potential (in volt) required to stop photo electrons when light of wavelength 200nm is

Given ϕ=4.7eV for λ=100nm, Vs​=7.7volt for λ=200nm Vs​=? eVs​=λch​−ϕ =2×10−7×1.6×10−193×108×6.62×10−34​−4.7 =6.2−4.7=1.5V ⇒Vs​=1.5volt

Given $ϕ = 4.7 e V$
for $λ = 100 nm,$
$V_{s} = 7.7 v o lt$
for $λ = 200 nm$
$V_{s} = ?$
$e V_{s} = \frac{c h}{λ} - ϕ$
$= \frac{3 \times 1 0 ^{8} \times 6.62 \times 1 0 ^{- 34}}{2 \times 1 0 ^{- 7} \times 1.6 \times 1 0 ^{- 19}} - 4.7$
$= 6.2 - 4.7 = 1.5 V$
$\Rightarrow V_{s} = 1.5 v o lt$