The electric field of light wave is given as   E   → = 10 – 3 cos ⁡ 2 π x 5…

The electric field of light wave is given as  E =103cos2πx5×107-2π×6×1014 tx^NC . This light falls on a metal plate of work function 2 eV . The stopping potential of the photo-electrons is:
Given, E (in eV ) =12375λ(in Å)
  1. 0.72 V
  2. 2.0 V
  3. 2.48 V
  4. 0.48 V

Solution

E=10-3cos2πx5×10-7-2π×6×1014tx^N/c
k=2π5×10-7
And ω=6×1014×2π f=6×1014Hz
E=ϕ+KEmax
KEmax=hf-ϕ
=6.6×10-34×6×10141.6×10-19-2
=2.475-2=0.48 eV
Stopping potential is 0.48V

Asked in: JEE Main 2019 (09 Apr Shift 1)

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