Paper 1 Wave-Particle Duality Answers

Q	Answer	Reason
1	A	Duality is evidence-dependent modelling.
2	A	Photon energy depends on $f$.
3	A	Diffraction/interference are wave signatures.
4	C	The de Broglie relation is $\lambda =h/p$.
5	A	Inverse relation.
6	A	Diffraction is significant when dimensions match wavelength scale.
7	A	Photon momentum relation.
8	A	Localized hits plus interference pattern.
9	B	Larger kinetic energy gives larger momentum and shorter wavelength.
10	B	Avoid naive simultaneous classical pictures.
11	A	Electron diffraction from crystals.
12	D	Work done by the accelerating p.d. becomes kinetic energy: $K=eV$.
13	A	$\lambda =h/mv$ non-relativistically.
14	B	Appreciable diffraction requires wavelength comparable to the relevant crystal-plane spacing.
15	A	Wave model predicts gradual energy absorption, contrary to threshold/no delay.
16	A	Classical particles do not diffract/interfere.
17	C	Threshold-frequency photoemission and one-photon energy transfer support the particulate model.
18	C	$\lambda =h/p$ is tiny for macroscopic momentum.
19	B	Both $E=hc/\lambda$ and $p=h/\lambda$ decrease when wavelength increases.
20	D	Since $\lambda =h/p$, doubling $p$ halves $\lambda$.