A powerpoint about photoelectric effect about the photoelectric effect for AQA Physics.

1. Photoelectric
Effect
Objective
•Describe the photoelectric effect
•To complete the calculations provided
on the photoelectric effect.

2. Photons
• We can imagine photons as little particles of light.
Each one has energy E=hf.
• If we increase the amount of light being
produced, each particle still contains as much
energy but there are now more of them.
• In the photoelectric effect however, it is the
frequency of each particle not the number that
matters.

3. Releasing electrons
• Metals contain free electrons in
their structure.
• To bring electrons from this state
just to the edge of the metal they
require a certain amount of
energy.
• This energy is called the work
function, ‘Φ’.
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4. Releasing electrons
• To release the electron the
energy provided by a photon (hf)
must at least meet the
magnitude of Φ.
• hf = Φ
• When hf > Φ the extra energy
will go into kinetic energy.
• K.E. = hf - Φ
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5. Why frequency of a photon not
numbers of photons?
• The photons of light can’t add up their
individual energies to produce enough to
ionise an electron. One on its own must have
enough energy.
• A small boy tries to dislodge a coconut by throwing a ping-
pong ball at it – no luck, the ping-pong ball has too little
energy! He then tries a whole bowl of ping-pong balls but the
coconut still stays put! Along comes a physicist with a pistol
who fires one bullet at the coconut which knocks it off its
support.