Question

When a metal surface is illuminated by light of wavelength 400 nm and 250 nm, the maximum velocities of the photoelectrons ejected are v and 2v respectively. The work function of the metal is (h = Planck’s constant, c = velocity of light in air)

• A. \(2hc \times 10^6\ \text{J}\)
• B. \(1.5hc \times 10^6\ \text{J}\)
• C. \(hc \times 10^6\ \text{J}\)
• D. 0.5hc × 10⁶ J

Hint:

Higher frequency light increases kinetic energy, not work function.

Answer 1

The Correct Option is C

Step 1: Einstein’s photoelectric equation (hc)/(λ) = φ + (1)/(2)mv²
Step 2: For given data, solving simultaneous equations gives φ = hc × 10⁶ J