DP Physics (last assessment 2024)

Question 23M.2.HL.TZ1.a

Date	May 2023	Marks available	[Maximum mark: 4]	Reference code	23M.2.HL.TZ1.a
Level	HL	Paper	2	Time zone	TZ1
Command term	Calculate	Question number	a	Adapted from	N/A

[Maximum mark: 4]

23M.2.HL.TZ1.a

Photons of wavelength 468 nm are incident on a metallic surface. The maximum kinetic energy of the emitted electrons is 1.8 eV.

Calculate

(i)

the work function of the surface, in eV.

[2]

Markscheme

Use of E_max = $\frac{h c}{λ} - ϕ \Rightarrow ϕ = \frac{h c}{λ} -$ E_max✓

$ϕ =$ « $\frac{h c}{λ}$ − E_max = $\frac{(6.63 \times 10^{- 34}) (3 \times 10^{8})}{(468 \times 10^{- 9}) (1.6 \times 10^{- 19})}$ − 1.81» = 0.85625 $\approx$ 0.86 «eV» ✓

(ii)

the longest wavelength of a photon that will eject an electron from this surface.

[2]

Markscheme

Use of $\frac{h c}{λ} = ϕ \Rightarrow λ = \frac{h c}{ϕ}$ ✓

$λ =$ « $\frac{(6.63 \times 10^{- 34}) (3 \times 10^{8})}{(468 \times 10^{- 9}) (1.6 \times 10^{- 19})}$ =» 1.45 × 10⁻⁶ «m»✓

Allow ECF from a(i)

Syllabus sections

Core

Core » Topic 7: Atomic, nuclear and particle physics » 7.1 – Discrete energy and radioactivity

Core » Topic 1: Measurements and uncertainties » 1.2 – Uncertainties and errors

Core » Topic 1: Measurements and uncertainties

Core » Topic 7: Atomic, nuclear and particle physics

Question 23M.2.HL.TZ1.a

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