Page 13 - PRE-U STPM PHYSICS TERM 2

Physics Term 2 STPM Chapter 13 Capacitors

ANSWERS

1 3. D 4. A 5. C 6. D
C
7. A: Q = ( )V and Q = (2C)V
Q 24 mC 1 2 2
1. C = = = 2 mF
13 V 12 V 8. (a) (i) 0.5 µF (ii) 6 µC 13
2. (a) Q = CV = (50 µF)(3.0 V) = 150 µC (b) (i) 2 µF (ii) 12 µC
(b) Q = (50 µF)(6.0 V) = 300 µC (c) (i) 8 µF (ii) 24 µC
(d) (i) 0.8 µF (ii) 9.6 µC, 4.8 µC
Q
9. (a) Two 2 µF capacitors in series with 2 × 10 V.
(b)

0
V
20 V
3. Q = (100)V = (50)(12) 20
1 10. (a) — µC
V = 6 V 3
1
(b) 44.4 V 2Q = (C + C ) V
2 1 2
11. (b) (C + C )V = C V + C V
1 2 1 1 1 2 2
ε A (C V + C V )
1. C = 0 V = ——–———
1
1
2
2
d 1 (C + C )
–3
Cd (6.0n) (2.0 × 10 ) 1 2
A = = = 1.36 m 2
ε 8.85 × 10 –12
0 5
–12
ε A (8.85 × 10 )(0.04)
2. (a) C = 0 = –3 = 7.08 × 10 F 1. C: Same charge Q on all capacitors.
–11
d 5 × 10
Q
V Potential difference across capacitor C , V = —–

(b) (i) E = , 1 1 C
d 1 1 1
2. A: U = —CV , U’ = —(ε C)V = ε U
2
2
V = E d 2 2 r r
max max
–3
6
d = (3.0 × 10 )(5 × 10 ) 3. D 4. C 5. A 6. B 7. B 8. C
4
= 1.50 × 10 V
9. (a) 5 µC Q = CV
–6
(ii) Q = CV = 1.06 × 10 C
max max 1
–4
(b) 1.25 × 10 J U = –– CV 2
3. Final charge, Q = CV = (24 m)(6.0 V) 2
–4
= 144 mC (c) 2.50 × 10 J W = QV
Q (d) 1.25 × 10 J (iii) – (ii)
–4
Time taken, t = = 96 s
I 1
10. (a) 1.25 J U = –– CV 2
2
3 1 Q 2
(b) 0.25 J U = –– ——–—
2 (C + C )
1 2
1. C 2. B Energy dissipated as heat = 1.00 J
3. 1.42 × 10 F C = 2 × —–––)
(
ε ε A
r 0
–8
2
1
1
1
2
d 11. (a) (C + C ) V = C V + C V 2
(C V + C V )
1
1
2
2
4 V = ——–——–
(C + C )
1 2
–2
(b) 2.0 × 10 J
1. A
–7
2. D: Capacitor X: Q = CV 12. (a) 1.00 ×10 C Q = CV
Q
′
Capacitors X and Y in parallel. (b) (i) 1 000 V V = —
C
Same V, same Q. 1 1
–5
2
(ii) 4.0 × 10 J W = –– C V – –– CV 2
2 1 1 2
78
13 Physic T2.indd 78 10/18/18 3:18 PM