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A student performs an experiment on phot...

A student performs an experiment on photoelectric effect, using two materials A and B. A plot of `V_(stop)` vs `nu` is given in fig.
(i) Which material A or B has a higher work function?
(ii) Given the electric charge of an electron `=1.6xx10^(-19)C`, find the value of h obtained from the experiment for both A and B. Comment on whether it is consistent with Einstein's theory.

Text Solution

Verified by Experts

(i) Given, thresholed frequency of A is given by `v_(OA)=5xx10^(14)` Hz and
For B, `" "v_(OB)=10xx10^(14)Hz`
We know that
Work function, `" "phi=hv_(0)or phi_(0)propv_(0)`
`implies" "phi_(0)propv_(0)`
So, `" "(phi_(OA))/(phi_(OB))=(5xx10^(14))/(10xx10^(14))lt1`
`implies" "phi_(OA)ltphi_(OB)`
Thus, work function of B is higher than A.
(ii) For metal A, slope `=h/e=(2)/((10-5)10^(14))`
or `" "h=(2e)/(5xx10^(14))=(2xx1.6xxxx10^(-19))/(5xx10^(14))`
`" "=6.4xx10^(-34)Js`
For metal B, slope `=h/e=(2.5)/((15-10)10^(14))`
or `" "h=(2.5xx e)/(5xx10^(14))=(2.5xx1.6xx10^(-19))/(5xx10^(14))`
`" "=8xx10^(-34)Js`
Since, the value of h from experiment for metals A and B is different. Hence, experiment is not consistent with theory.
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