Tessellate - S.T.E.M.S - Physics - School - Set 2 - Problem 3

Electricity and Magnetism Level 3

A metal plate when exposed to light of wavelength λ \lambda photoelectrons are ejected. When a retarding electric field of intensity E E is applied, none of the photoelectrons can move away from the plate farther than a certain distance d d . Which of the following is a correct expression for the threshold wavelength λ t h \lambda_{th} ?

This problem is a part of Tessellate S.T.E.M.S.

λ t h = ( 1 λ − e E d h c ) − 1 \lambda_{th}= (\frac{1}{\lambda}-\frac{eEd}{hc})^{-1} λ t h = λ − h c e E d \lambda_{th}= \lambda-\frac{hc}{eEd} \qquad λ t h = h c e E d \lambda_{th}= \frac{hc}{eEd} \qquad None of these

Writabrata Bhattacharya by Writabrata Bhattacharya , 22, India

This section requires Javascript.
You are seeing this because something didn't load right. We suggest you, (a) try refreshing the page, (b) enabling javascript if it is disabled on your browser and, finally, (c) loading the non-javascript version of this page . We're sorry about the hassle.

1 solution

Einstein's photoelectric equation gives λ t h = ( 1 λ − m e v 2 2 h c ) − 1 \displaystyle \lambda_{th} = \left(\dfrac{1}{\lambda}-\dfrac{m_e v^2}{2hc}\right)^{-1} . Now since it stops after moving a distance d d we have d = v 2 m e 2 e E \displaystyle d=\dfrac{v^2 m_e}{2eE} which when substituted gives the answer as λ t h = ( 1 λ − e E d h c ) − 1 \displaystyle \lambda_{th} = \left(\dfrac{1}{\lambda}-\dfrac{eEd}{hc}\right)^{-1}

0 Helpful 0 Interesting 0 Brilliant 0 Confused

0 pending reports

×

Problem Loading...

Note Loading...

Set Loading...