Edexcel IGCSE Physics 3 Waves Question Bank

any two from:

- both electromagnetic waves;

- both transfer energy;

- both transverse waves;

- both are non-ionising;

- both can travel through vacuum;

- both have same speed (in a vacuum);

allow EM waves
allow both part of EM
spectrum
allow both can be reflected / refracted /
diffracted

- infrared has longer / higher wavelength
- infrared has lower frequency

Accept:
- reverse argument

Condone:
- infrared has lower energy

For 1 mark:
- light refracts / bends / changes direction / changes speed / changes wavelength

For 2 marks:
- light refracts / bends towards normal
- light slows down
- wavelength decreases

normal;

$\sin (\mathrm{c})=1 / \mathrm{n} ;$

Notes: allow in words and
rearrangements

- substitution
- rearrangement
- evaluation

Example:
- sin(c) = 1 / 1.6
- c = sin^-1(0.625)
- c = 39 degrees

Accept:
- 38.68...

- total internal reflection at the glass/air boundary
- angle of incidence = angle of reflection

Accept:
- ECF from 10(a)(iv) that would suggest refraction, e.g. if answer to 10(a)(iv) is greater than 50 degrees

Marking guidance:
- Judge by eye.

amplitude in the range 0.8-0.9 cm

radio waves

Accept:
- radio
- radio frequency

Reject:
- radioactive waves
- radiation waves

Marking points:
- substitution
- rearrangement
- evaluation

Example:
$$3.0\times10^{8}=f\times0.027$$$$f=\frac{3.0\times10^{8}}{0.027}$$$$f=1.1\times10^{10}\ \mathrm{Hz}$$

Accept:
- wavelength substitution in $\mathrm{cm}$ or $\mathrm{m}$
- $1.11\ldots\times10^{10}\ \mathrm{Hz}$

Marking guidance:
- Deduct 1 mark for a power-of-ten error.