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C12.1 Current and charge AQA AS Physics C12 Electricity Kerboodle Answers: Page No. 203
1.Ans- a
i)
3.5 c
ii in 10 min.
210 c
b Calculate the average current in a wire through which a charge of 15 C passes in i ss,
3.0A
ii 100 s.
0.15 A
2.Ans-
a HA
3.8x 1015
b S.OA.
1.9 x 1022
3.Ans-
a the charge flowing along the beam each minute
72 mC
b the number of electrons that pass along the beam each minute.
4.5 x 1017
4 .ANS-
1600 s
b 0.1 A.
8000 s
12.2 Potential difference and power AQA AS Physics C12 Electricity Kerboodle Answers : Page No. 205
1.
29kJ
b O.OSX
720J
2.a )the current through the light bulb
2.0A
b the energy transfer to the light bulb in 1800 s.
22kJ
3. i) 48kJ
ii 3.5A
4.a) 12 kJ
b.
4.5W
c 2700s
12.3 Resistance AQA AS Physics C12 Electricity Kerboodle Answers: Page No. 208
1.
6.0.0, I OV, 0.125 mA, 160.0, 2.5 mA
b 7.5.0
2.Ans-
310
3.Ans-
o.11mo
4.a 1.8 x10-6 nm
b33mm
12.4 Components and their characteristicsAQA AS Physics C12 Electricity Kerboodle Answers : Page No. 211
1.a.0.25A, 12D
b The filament would become brighter and hotter until it melts and breaks as a result.
2.Ans-
a at20’C
0.03mA
3.a.
b The diode would then be ‘reverse-biased’ so the current in the circuit would be negligible.
4.a. the resistance at SO ‘C
30.4 n
b. the temperature when the resistance is 30.00.
46°C
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Practice questions: Page No. 212-213
(b)
(c)
2 .(a) ΔQ = I Δt = 40 × 10-3 × 3 × 60
= 7.2 C
(b)
(c)
(d)
3 (a)
(b)
Current is zero for all negative voltages
For positive voltages, curve showing a steep rise in current starting at about +0.6 V (with voltage not greatly to exceed 1 V)
4.
.
(a)
(i) Readings need to be taken more quickly than could be achieved by manual timing
(ii) Rate: more than 40 samples per second
Reason: the current rises very rapidly over the first 0.1 s, and you should have about 4 results on this first section
(b) Initial resistance is low so initial current is high
• Temperature of filament increases (or filament heats up)
• Resistance increases as temperature rises
• Increase in resistance causes current to fall
• Current is steady when energy supplied = energy lost from filament (or when temperature is constant)
• Maximum heating is produced at start when current is highest
• Melting of filament causes it to fail (could be mechanical failure caused by temperature rise)
• When switched on energy is supplied more rapidly than it is lost so filament melts
5. (a)
(b).
6. (a)
(i)Circuit to show:
• Battery, switch, wire, variable resistor and ammeter in series
• Voltmeter in parallel with wire
(ii) Switch on, measure I and V
Change length of wire
Measure new I and V
Measure length of wire each time
(iii)
(b)
7 (a)
(i)
A component (or substance) which has no electrical resistance
(ii)• Correct high temperature graph with abrupt discontinuous vertical line indicating that R has become zero at a certain temperature
• Temperature axis labelled (e.g. Transition) at the corresponding temperature
(b)
Reason:
When resistance is zero there is no energy (heat, or power) lost
Applications:
Power cables, electromagnets, generators, motors, transformers, MRI scanners, monorail trains, particle accelerators, fusion reactors.
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References:
BBC Bitesize
AQA GCSE Science Kerboodle textbook
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