Practice Photoelectric Effect in Physics

Use these practice problems to test your method after reviewing the concept explanation and worked examples.

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Quick Recap

The photoelectric effect is the emission of electrons from a material when light of high enough frequency shines on it.

Light can hit a surface like tiny packets of energy and knock electrons out.

Showing a random 20 of 50 problems.

Example 1

medium

Doubling the intensity of monochromatic light above threshold doubles the ___ but does not change

KE_{\max}

Example 2

medium

A photon of frequency

8\times10^{14} \text{ Hz}

hits a metal with work function

3.3\times10^{-19} \text{ J}

. Find

KE_{\max}

. (

h = 6.6\times10^{-34}

)

Example 3

challenge

Photon energy

E

just exceeds work function

\phi

KE_{\max} = 0.1\phi

. Express

E

in terms of

\phi

Example 4

medium

The stopping potential for ejected electrons is

1.5 \text{ V}

. Find their maximum kinetic energy (

e = 1.6\times10^{-19} \text{ C}

Example 5

easy

Find the energy of a photon with frequency

f = 6\times10^{14}\text{ Hz}

. (

h = 6.6\times10^{-34}

)

Example 6

easy

Does increasing the brightness (intensity) of light below the threshold frequency cause electron emission?

Example 7

medium

Two metals have work functions

\phi_1 = 2\times10^{-19}

and

\phi_2 = 5\times10^{-19} \text{ J}

. For the same photon energy, which emits faster electrons?

Example 8

medium

A graph of

KE_{\max}

versus

f

has slope

h

and

y

-intercept

-\phi

. If the slope is

6.6\times10^{-34}\text{ J s}

and intercept is

-3.3\times10^{-19}\text{ J}

, find the threshold frequency.

Example 9

easy

Express the work function

\phi = 4.8\times10^{-19}\text{ J}

in electronvolts. (

1\text{ eV} = 1.6\times10^{-19}\text{ J}

)

Example 10

medium

Two metals have

\phi_A = 2.0\text{ eV}

and

\phi_B = 4.0\text{ eV}

. Identical photons of

E = 5.0\text{ eV}

hit each. Which emits faster electrons?

Example 11

medium

Light of energy

6\times10^{-19} \text{ J}

ejects electrons with

KE_{\max} = 2\times10^{-19} \text{ J}

. Find the work function.

Example 12

easy

Above threshold, increasing light intensity changes the ___ of emitted electrons.

Example 13

medium

The stopping potential is

2 ext{ V}

. Find the maximum kinetic energy of the electrons (

e = 1.6 imes10^{-19} ext{ C}

Example 14

medium

A photon of frequency

6 imes10^{14} ext{ Hz}

hits a metal with work function

2.6 imes10^{-19} ext{ J}

. Find

KE_{\max}

. (

h = 6.6 imes10^{-34}

)

Example 15

challenge

Light of

\lambda = 200\text{ nm}

shines on a metal with

\phi = 3.0\text{ eV}

. Find

KE_{\max}

in eV. (

h = 6.6\times10^{-34}

c = 3\times10^8

1\text{ eV} = 1.6\times10^{-19}\text{ J}

)

Example 16

easy

If a metal's work function is

\phi = 3\times10^{-19} \text{ J}

and a photon delivers

5\times10^{-19} \text{ J}

, find the maximum kinetic energy of the electron.

Example 17

easy

In the photoelectric effect, light behaves more like a wave or like particles (photons)?

Example 18

medium

A metal emits electrons with

KE_{\max} = 1.5\times10^{-19}\text{ J}

under light of

f = 7\times10^{14}\text{ Hz}

. Find

\phi

. (

h = 6.6\times10^{-34}

)

Example 19

medium

A photon has wavelength

\lambda = 4\times10^{-7} \text{ m}

. Find its energy. (

h = 6.6\times10^{-34}

c = 3\times10^8

)

Example 20

medium

The stopping voltage for ejected electrons is

V_s = 0.8\text{ V}

. Find their maximum kinetic energy (

e = 1.6\times10^{-19}\text{ C}

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