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Question 18M.2.HL.TZ1.8b.ii

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Date May 2018 Marks available [Maximum mark: 2] Reference code 18M.2.HL.TZ1.8b.ii
Level HL Paper 2 Time zone TZ1
Command term Suggest Question number b.ii Adapted from N/A
b.ii.
[Maximum mark: 2]
18M.2.HL.TZ1.8b.ii

Hydrogen atoms in an ultraviolet (UV) lamp make transitions from the first excited state to the ground state. Photons are emitted and are incident on a photoelectric surface as shown.

M18/4/PHYSI/HP2/ENG/TZ1/08

The photons cause the emission of electrons from the photoelectric surface. The work function of the photoelectric surface is 5.1 eV.

(b.ii)

Suggest, with reference to conservation of energy, how the variable voltage source can be used to stop all emitted electrons from reaching the collecting plate.

[2]

Markscheme

EPE produced by battery

exceeds maximum KE of electrons / electrons don’t have enough KE

 

For first mark, accept explanation in terms of electric potential energy difference of electrons between surface and plate.

[2 marks]

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