Saved Bookmarks
| 1. |
Radiation of wavelength `lambda` in indent on a photocell . The fastest emitted electron has speed `v` if the wavelength is changed to `(3 lambda)/(4)` , then speed of the fastest emitted electron will beA. `v((3)/(4))^((1)/(2))`B. `v((4)/(3))^((1)/(2))`C. less than `v((4)/(3))^((1)/(2))`D. greater than `v((4)/(3))^((1)/(2))` |
|
Answer» Correct Answer - D `(1)/(2)mv^2=(4hc)/(3lamda)-W_0` Let the speed of the fastest electron be `V_1` when excitation wavelength is changed to `(3lamda)/(4)`. `(1)/(2)mv_1^2=(4hc)/(3lamda)-W_0` `implies(1)/(2)mv_1^2=(4)/(3)((hc)/(lamda)-W_0)+(W_0)/(3)` `implies(1)/(2)mv_1^2=(4)/(3)((1)/(2)mv^2)+(W_0)/(3)` `impliesv_1^2=(4v^2)/(3)+(2W_0)/(3m)` `v_1gtsqrt((4)/(3))v` |
|