The threshold frequency of a metal with work function 6.63 eV is :

Solution

Physics sir · 4 steps

Turn the work function into joules, then divide by h; the 6.63 cancels neatly.

1. Threshold condition. At the threshold frequency ν₀, one photon has just enough energy to free an electron. So the photon energy equals the work function, and the electron leaves with zero kinetic energy.

   φ = hν₀ ⇒ ν₀ = φ/h

2. Convert to joules. φ = 6.63 eV = 6.63 × 1.6 × 10⁻¹⁹ J. Leave it in this form, because h = 6.63 × 10⁻³⁴ J s also has 6.63 in it.
3. Divide by h. ν₀ = (6.63 × 1.6 × 10⁻¹⁹)/(6.63 × 10⁻³⁴) = 1.6 × 10⁻¹⁹⁺³⁴ = 1.6 × 10¹⁵ Hz.
4. So. The threshold frequency is 1.6 × 10¹⁵ Hz, option (c).

The idea to keep. Threshold frequency is just ν₀ = φ/h. Convert eV to joules with 1.6 × 10⁻¹⁹, and watch the powers of ten when you divide.

Answer from the NTA final answer key. Solution by PrepWiser.