Chapter 7, Problem 7.21QP

(a)

Interpretation Introduction

Interpretation:

From the work function of potassium, the minimum light frequency required to eject electrons has to be calculated.

Concept introduction:

Electrons present in metals are held by attractive force.  It requires higher frequency of light to eject electrons.  When the energy of photon matches the energy that binds metal electrons, then the light can free electrons from metals.  When higher frequency of light is used it not only eject electrons but also acquires some kinetic energy.  The equation to study photoelectric effect is given as

$\text{hν}\text{=}\text{KE}\text{+}\text{W}$

W is work function.

KE is kinetic energy.

h is Planck’s constant

$\text{ν}$ is frequency.

(b)

Interpretation Introduction

Interpretation:

From the work function of potassium and frequency, the kinetic energy of ejected electrons has to be calculated.

Concept introduction:

Electrons present in metals are held by attractive force.  It requires higher frequency of light to eject electrons.  When the energy of photon matches the energy that binds metal electrons, then the light can free electrons from metals.  When higher frequency of light is used it not only eject electrons but also acquires some kinetic energy.  The equation to study photoelectric effect is given as

$\text{hν}\text{=}\text{KE}\text{+}\text{W}$

W is work function.

KE is kinetic energy.

h is Planck’s constant

$\text{ν}$ is frequency.