Dual Nature of Radiation and Matter - Result Question 62

«««< HEAD:content/english/neet-pyq-chapterwise/physics/dual-nature-of-radiation-and-matter/dual-nature-of-radiation-and-matter-result-question-62.md

66. If the threshold wavelength for a certain metal is $2000 \AA$, then the work-function of the metal is

======= ####66. If the threshold wavelength for a certain metal is $2000 \AA$, then the work-function of the metal is

3e0f7ab6f6a50373c3f2dbda6ca2533482a77bed:content/english/neet-pyq-chapterwise/physics/dual-nature-of-radiation-and-matter/dual-nature-of-radiation-and-matter—result-question-62.md (a) $6.2 J$

(b) $6.2 eV$

(c) $6.2 MeV$

(d) $6.2 keV$

[1995]

Show Answer

Answer:

Correct Answer: 66. (b)

Solution:

  1. (b) Threshold wavelength $(\lambda)=2000 \AA$

$=2000 \times 10^{-10} m$.

Work function $(W)=\frac{h c}{\lambda}$

$ \begin{aligned} = & \frac{(6.6 \times 10^{34}) \times(3 \times 10^{8})}{2000 \times 10^{-10}} \\ & =9.9 \times 10^{-19} J=\frac{9.9 \times 10^{-19}}{1.6 \times 10^{-19}}=6.2 eV \end{aligned} $