Question

Maximum velocity of the photoelectrons emitted by a metal surface is 1.2 × 10⁶ms^–1 . Assuming the specific charge of the electron to be 1.8 × 10¹¹ C Kg^–1, the value of the stopping potential in volt will be-

• A. 2
• B. 3
• C. 4
• D. 6

Answer 1

Answer: (C)

4

Answer 2

$\frac { 1 } { 2 }$ mv² = eV₀

V₀ = $\frac { 1 } { 2 }$ $\frac { \mathrm { m } } { \mathrm { e } }$ v²

V₀ = $\frac { 1 } { 2 }$ × $\frac { 1 } { 1.8 \times 10 ^ { 11 } }$ × (1.2 × 10⁶)² = 4 Volt