Question

In a photo electric experiment, the graph of frequency of incident light (in Hz) and stopping potential V(inV)is as shown in the figure. From figure, The value of the Planck’s constant is (e is the elementary charge) fig:

• A.
• B.
• C.
• D.

Answer 1

Answer: (A)

Answer 2

: According to Einstein’s photoelectric equation

Where$\phi _ { 0 }$is the work function , is the incident frequency and h is the planck’s constant

Also

Where e is the elementary charge, V is the stopping potential

Hence the graph between v and is a straight line and slope of this graph is given by

Slope $= \frac { h } { e }$……. (i)

From the graph in the question

Slope $= \frac { a b } { b c }$…. (ii)

From (i) and (ii) we get

$h = e \frac { a b } { b c }$