With reference to the photoelectric effect, state what is meant by work function energy.

1. (a)With reference to the photoelectric effect, state what is meant by work function energy.[2]
2. (b)(i)The work function energy of a clean metal surface is 5.5 × 10⁻¹⁹J. Electromagnetic radiation of wavelength 280 nm is incident on the metal surface. The metal is in a vacuum. Calculate: 1. the photon energy photon energy = ........................................................... J[2]
3. (b)(i) 2.the maximum speed V_MAX of the electrons emitted from the surface. V_MAX = ........................................................... ms⁻¹[3]
4. (b)(ii)Explain why most of the emitted electrons will have a speed lower than V_MAX[1]
5. (c)The electromagnetic radiation incident on the metal surface may change in intensity or in frequency. Complete [Figure 11.1] by inserting either 'increases' or 'decreases' or 'no change' to describe the effects of the changes shown on the maximum speed and on the rate of emission of electrons.[4]

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