Practicing Success
A specific metal's work function is 4.2 eV. Will this metal emit photoelectrically for incident light with a 330 nm wavelength? Also mark the correct reason for the answer. |
Yes, because \(\nu \)>\(\nu \)0 No, because \(\nu \)<\(\nu \)0 Yes, because \(\nu \)<\(\nu \)0 No, because \(\nu \)>\(\nu \)0 |
No, because \(\nu \)<\(\nu \)0 |
The minimum threshold frequency is given by \(\nu \)0 = \(\phi\)0/h metal's work function \(\phi\)0 = 4.2 eV h = 6.6×10-34 Js So, \(\nu \)0 = 4.2×1.6×10-19/6.6×10-34 \(\nu \)0 = 1.018×1015 Hz ...............................(1) the relation between frequency and wavelength is given by \(\nu \) = c/\(\lambda \) = 3 × 108/330 × 10-9 =0.9 ×1015 Hz .................................(2) So from ...(1) and ...(2) it is clear that \(\nu \)<\(\nu \)0, so this metal will NOT emit photoelectrically. |