Question

The work function of caesium is 2.14 eV, find the threshold frequency for caesium.
(Ans: 5.164 x 10¹⁴ Hz.)

Answer 1

Work function = planks constant × threshold frequency

First convert work function into joules by multiplying it to 1.6 × 10^-19

Answer 2

Answer:

Threshold frequency = 5.164 x 10¹⁴ Hz.

Explanation:

Given,

Work function of caesium = 2.14 eV

We have to find the work function of the caesium.

As we know charge,

$1\ eV\ =\ 1.6\times 10^{-19}$

$=>\ 2.14\ eV\ =\ 2.14\times 1.6\times 10^{-19}\ J$

                   $=\ 3.424\times 10^{-19}\ J$

Threshold frequency can be given by ,

$f\ =\ \dfrac{work\ function}{planck's\ constant}$

   $=\ \dfrac{3.424\times 10^{-19}}{6.625\times 10^{-34}}$

           = 5.164 x 10¹⁴ Hz.

Hence, the threshold frequency of the caesium will be 5.164 x 10¹⁴ Hz.