A-LevelPhysicsQuantum physics9702/43 · Oct/Nov 2021 · Q109 Marks
State an experimental phenomenon that provides evidence for: the particulate nature of electromagnetic radiation
- (a)(i)State an experimental phenomenon that provides evidence for: the particulate nature of electromagnetic radiation[1]
- (a)(ii)the wave nature of matter.[1]
- (b)(i)A particle of matter moves with momentum p. State the equation that gives the effective wavelength λ of the particle. State the name of any other symbols used.[2]
- (b)(ii)State the name given to the wavelength of the moving particle.[1]
- (c)(i)Electrons are accelerated from rest through a potential difference (p.d.) of 4.8kV. Show that the final speed of the electrons is 4.1 x 10⁷ m s⁻¹.[2]
- (c)(ii)Calculate the effective wavelength of a beam of electrons moving at the speed in (c)(i).[2]
Mark scheme
Marking points from the official mark scheme (Oct/Nov 2021). The mark or mark type is shown in brackets.
- [B1] photoelectric effect
- [B1] electron diffraction
- [M1] λ = h/p
- [A1] h is the Planck constant
- [B1] de Broglie (wavelength)
- [C1] 1/2mv² = eV
- [A1] 1/2 x 9.11 x 10⁻³¹ x v² = 1.60 × 10⁻¹⁹ × 4800 so v = 4.1 × 10⁷ m s⁻¹
- [C1] λ = h/mv
- [A1] = 6.63 × 10⁻³⁴ / (9.11 × 10⁻³¹ × 4.1 × 10⁷) = 1.8 x 10⁻¹¹ m
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