y12 mark scheme

6733 Unit Test PHY3 (Topics)
Topic A - Astrophysics
(a)
H-R Diagram
L and T
L􀁾 and K
[or L and L􀁾 􀀹, T and K 􀀹, not W]
Any 2 correct [of 102, 1 or 100, 10−2]
All 3 correct
20 000 and 5 000
(iv) Identify stars
Red giant = (B and) C
Low mass ms star = E [ignore X]
2
(v) Zeta Tauri Luminosity
Use of L = 4 π D2 I
Correct substitution
3.8(2) × 1030 (W) 3
(vi) Zeta Tauri identification (ecf)
3.8(2) × 1030 W ÷ 3.9 × 1026 W [or 4 × 1030 W used]
Correct ratio [e.g. 9700, 9800, 10300 or 104, etc.]
Hence A [from answer in range 9700 to 10300]
3
(b)
Fusion calculations
Mass difference substitution [(2 × 5.0055) – (6.6447 + 2 × 1.6726)]
2.11 × 10−29 kg [or 0.0211 × 10−27 kg]
E = mc2 seen
1.9 × 10-12 J [ecf]
2
2
(c)(i)Pulsars
Neutron star
Core remnant
Supernova
1.4 [accept 0.4 and 1.4]
4
(ii) (iii)
Binary pulsar system
Quality of written communication
(Varying) radio signals
(Regular) pulses detected [like lighthouse]
Idea of two overlapping pulses (from same location) 4

Black hole
1
(d)
White dwarf density
M ÷4/3 π r3 [allow M, m, R, r] 1
Any pair of values correctly read [may be implied, ignore 106]
Any correct substitution [with 2.0 × 1030 and 106, ecf on (i)]
Two correct answers [in kg m-3, no statement required]
White dwarf future
Cools / temperature decreases 3
Becomes dimmer / changes colour [not brown dwarf] 1
Total 32