Chapter 6.3, Problem 1PPC

Interpretation Introduction

Interpretation:

The velocity of the blue ball is to be determined, if it is struck by a red ball moving at 1.75 m/s, with given masses of the balls.

Concept introduction:

In photoelectric effect, the light incident on the metal surface would eject electrons only if it has certain minimum frequency called threshold frequency. It can be represented as

$E=\text{h}\nu$

Here, $E$ is the energy of photon, $\text{h}$ is Planck’s constant, and $\nu$ is the threshold frequency.

The intensity (or brightness) of light is directly proportional to the number of electrons ejected. If the frequency is below the threshold frequency, then no electron will be ejected even for the brightest light.

The expression for the kinetic energy (K.E) of the ejected electron is as follows:

$\text{K}\text{.E}=\text{h}\nu -W$

Here, W is the binding energy of electron in metal.