A photosensitive metal has threshold frequency 3.3 × 10¹⁴ Hz. Light of frequency 8.2 × 10¹⁴ Hz is incident. Find the cut-off voltage in Vs, rounded to the nearest integer.
Physics · Photoelectric effect and dual nature of matter
JEE Mains Practice

Question

A photosensitive metal has threshold frequency 3.3 × 10¹⁴ Hz. Light of frequency 8.2 × 10¹⁴ Hz is incident. Find the cut-off voltage in Vs, rounded to the nearest integer.

G1 Physics · Accepted Answer

Step 1: Use Einstein's equation Kₘₐₓ = h(ν−ν₀) = eVₛ. Step 2: The threshold frequency ν₀ fixes the work function φ = hν₀. Step 3: Substitute the frequencies given in the question and solve for Kₘₐₓ or Vₛ. Final: 2.