AQA A-level Physics Measurements Mark Scheme

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Mark schemes
(a) 2.9% ✓
1
Allow 3%
1


(b) seen ✓
1

0.29 mm or 2.9 x 10-4 m✓ must see 2 sf only
1

(c) ± 0.01 mm ✓
1

(d) Clear indication that at least 10 spaces have been measured to give a spacing = 5.24
mm✓
spacing from at least 10 spaces
Allow answer within range ±0.05
1

(e) Substitution in d sinθ = nλ✓
The 25 spaces could appear here as n with sin θ as 0..5
1

d = 0.300 x 10-3 m so
number of lines = 3.34 x103✓
Condone error in powers of 10 in substitution
Allow ecf from 1-4 value of spacing
1

(f) Calculates % difference (4.6%) ✓
1

and makes judgement concerning agreement ✓
Allow ecf from 1-5 value
1

(g) care not to look directly into the laser beam✓
OR
care to avoid possibility of reflected laser beam ✓
OR
warning signs that laser is in use outside the laboratory✓
ANY ONE
1
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(a) Straight line of best fit passing through all error bars ✓
2




Look for reasonable distribution of points on either side
1

(b) h0 = 165 ± 2 mm✓
1

(c) Clear attempt to determine gradient ✓
1

Correct readoffs (within ½ square) for points on line more than 6 cm apart and
correct substitution into gradient equation ✓
1

h0k gradient =( -) 0.862 mm K-1 and
negative sign quoted ✓
Condone negative sign
Accept range -0.95 to -0.85
1


(d) k=

= 5.2 x 10-3 ✓
Allow ecf from candidate values
1

K-1 ✓
Accept range 0.0055 to 0.0049
1


(e) for h = 8000 mm, d-1 = ✓
1

d = 1.8 x 10-3 mm ✓
1
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