Question

The maximum velocity of the photoelectrons emited from the surface is v when light of frequency n falls on metal surface.If the incident frequency is increased to 3n,the maximum velocity of the ejected photo-electrons will be

• A. more than $\sqrt{3}$ v
• B. equal to $\sqrt{3}$ v
• C. v
• D. less than $\sqrt{3}$v

Answer 1

The correct option is B equal to $\sqrt{3}$ v

From Einstein's photo electric law: $E=h\upsilon =\frac{1}{2}m{v}^2$

Now,$\upsilon =n$

$nh=\frac{1}{2}m{v}^2$

$v=\sqrt{\frac{2nh}{m}}$

If frequency is inceased to 3n:

$v^{\prime }=\sqrt{3\times \frac{2nh}{m}}$

$v^{\prime }=\sqrt{3}v$