1.
State what is meant by phase difference.
[1 mark]
- how far out of step two waves are
JD SCIENCE
Module 4 Electrons, waves and photons
Indicative marking points. Award marks for equivalent scientific or mathematical wording. Do not issue this sheet with the student worksheet.
2.
State what is meant by superposition.
[1 mark]
- displacements add
3.
State what is meant by Young's double slits.
[1 mark]
- w = λD/s
4.
State what is meant by diffraction grating.
[1 mark]
- nλ = d sinθ
5.
State what is meant by stationary waves.
[1 mark]
- two opposite travelling waves of the same f
6.
State what is meant by the first harmonic.
[1 mark]
- λ/2 = L on a string
7.
State what is meant by refraction.
[1 mark]
- n = c/v = sin i / sin r
8.
State what is meant by optical fibre.
[1 mark]
- TIR along the core
9.
State what is meant by polarisation.
[1 mark]
- oscillations in one plane
10.
State what is meant by a photon in the photoelectric effect.
[1 mark]
- interacts with one electron
11.
Grace is asked about phase difference in a OCR Physics paper.
(a) [2 marks]
- in radians or degrees
(b) [3 marks]
- π rad is antiphase
12.
Grace is asked about superposition in a OCR Physics paper.
(a) [2 marks]
- constructive and destructive interference
(b) [3 marks]
- path difference nλ or (n+½)λ
13.
Grace is asked about Young's double slits in a OCR Physics paper.
(a) [2 marks]
- monochromatic coherent sources
(b) [3 marks]
- measures λ
14.
Grace is asked about diffraction grating in a OCR Physics paper.
(a) [2 marks]
- sharper maxima than two slits
(b) [3 marks]
- used to measure λ
15.
Grace is asked about stationary waves in a OCR Physics paper.
(a) [2 marks]
- nodes and antinodes
(b) [3 marks]
- harmonics on a string
16.
Grace is asked about the first harmonic in a OCR Physics paper.
(a) [2 marks]
- fundamental
(b) [3 marks]
- f = (1/2L)√(T/μ)
17.
w = λD/s. λ=6.0×10⁻⁷, D=1.5, s=0.50×10⁻³
[3 marks]
- Final answer: 1.8 mm
18.
nλ = d sinθ. n=1, d=2.0×10⁻⁶, θ=18°. λ
[3 marks]
- Final answer: 6.2 × 10⁻⁷ m
19.
First harmonic: L=0.80 m. λ
[3 marks]
- Final answer: 1.6 m
20.
n = 1.5, c=3.0×10⁸. v in glass
[3 marks]
- Final answer: 2.0 × 10⁸ m/s
21.
Critical angle if n=1.5 to air
[3 marks]
- Final answer: 41.8°
22.
Path difference for the 2nd bright fringe
[3 marks]
- Final answer: 2λ
23.
Grace carries out a OCR-style required practical linked to waves, superposition and optics. This is a typical OCR required-practical style question.
(a) [2 marks]
- Independent: the independent variable for this topic
- Dependent: the measured outcome
(b) [2 marks]
- keep all other variables constant
- so the test is fair / only one variable is changed
(c) [2 marks]
- repeat and calculate a mean / use a tighter method
24.
Grace carries out collecting valid data for waves, superposition and optics. This is a typical OCR required-practical style question.
(a) [2 marks]
- Independent: a chosen factor
- Dependent: a quantitative measurement
(b) [2 marks]
- calibrated instrument
- so the test is fair / only one variable is changed
(c) [2 marks]
- systematic error from zero error
25.
Grace carries out drawing a graph for waves, superposition and optics. This is a typical OCR required-practical style question.
(a) [2 marks]
- Independent: x-variable
- Dependent: y-variable
(b) [2 marks]
- same scale / same apparatus
- so the test is fair / only one variable is changed
(c) [2 marks]
- not drawing a line of best fit through the trend
26.
Grace carries out evaluating a method about waves, superposition and optics. This is a typical OCR required-practical style question.
(a) [2 marks]
- Independent: method change
- Dependent: precision / accuracy
(b) [2 marks]
- same sample size
- so the test is fair / only one variable is changed
(c) [2 marks]
- too few repeats
27.
Compare phase difference with superposition.
[4 marks]
- how far out of step two waves are
- displacements add
- give one linked difference
28.
Compare superposition with Young's double slits.
[4 marks]
- displacements add
- w = λD/s
- give one linked difference
29.
Compare Young's double slits with diffraction grating.
[4 marks]
- w = λD/s
- nλ = d sinθ
- give one linked difference
30.
Compare diffraction grating with stationary waves.
[4 marks]
- nλ = d sinθ
- two opposite travelling waves of the same f
- give one linked difference
31.
Apply your knowledge of refraction to this situation: towards the normal if slower
[3 marks]
- towards the normal if slower
32.
Apply your knowledge of optical fibre to this situation: cladding of lower n
[3 marks]
- cladding of lower n