1.
State what is meant by Ohm's law.
[1 mark]
- V=IR for a constant-temperature ohmic conductor
JD SCIENCE
Electric circuits
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 resistivity.
[1 mark]
- ρ = RA/L
3.
State what is meant by terminal pd.
[1 mark]
- ε = I(R+r) = V + Ir
4.
State what is meant by potential divider.
[1 mark]
- Vout = Vin × R2/(R1+R2)
5.
State what is meant by superconductivity.
[1 mark]
- zero resistivity below a critical temperature
6.
State what is meant by power in circuits.
[1 mark]
- P=VI=I²R=V²/R
7.
State what is meant by Kirchhoff 1.
[1 mark]
- conservation of charge
8.
State what is meant by Kirchhoff 2.
[1 mark]
- conservation of energy
9.
State what is meant by an emf.
[1 mark]
- energy transferred per coulomb by the source
10.
State what is meant by a semiconductor.
[1 mark]
- fewer charge carriers than a metal
11.
Devon is asked about Ohm's law in a Edexcel Physics paper.
(a) [2 marks]
- I–V graphs
(b) [3 marks]
- filament and diode are non-ohmic
12.
Devon is asked about resistivity in a Edexcel Physics paper.
(a) [2 marks]
- property of the material
(b) [3 marks]
- increases with T for metals
13.
Devon is asked about terminal pd in a Edexcel Physics paper.
(a) [2 marks]
- internal resistance
(b) [3 marks]
- lost volts
14.
Devon is asked about potential divider in a Edexcel Physics paper.
(a) [2 marks]
- sensors
(b) [3 marks]
- LDR and thermistor
15.
Devon is asked about superconductivity in a Edexcel Physics paper.
(a) [2 marks]
- no heating
(b) [3 marks]
- strong magnets / MRI
16.
Devon is asked about power in circuits in a Edexcel Physics paper.
(a) [2 marks]
- heating in cables
(b) [3 marks]
- choose thickness of wire
17.
I=V/R. 12 V, 4.0 Ω
[3 marks]
- Final answer: 3.0 A
18.
ρ=RA/L. R=2.0, A=0.50×10⁻⁶, L=2.0
[3 marks]
- Final answer: 5.0 × 10⁻⁷ Ω m
19.
ε=I(R+r). I=0.50, R=10, r=2.0
[3 marks]
- Final answer: 6.0 V
20.
Vout of 12 V across 1 kΩ and 3 kΩ (across 3 kΩ)
[3 marks]
- Final answer: 9.0 V
21.
Power in a 6.0 Ω resistor at 2.0 A
[3 marks]
- Final answer: 24 W
22.
Lost volts if I=0.40 A, r=1.5 Ω
[3 marks]
- Final answer: 0.60 V
23.
Devon carries out a Edexcel-style required practical linked to electricity. This is a typical Edexcel 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.
Devon carries out collecting valid data for electricity. This is a typical Edexcel 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.
Devon carries out drawing a graph for electricity. This is a typical Edexcel 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.
Devon carries out evaluating a method about electricity. This is a typical Edexcel 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 Ohm's law with resistivity.
[4 marks]
- V=IR for a constant-temperature ohmic conductor
- ρ = RA/L
- give one linked difference
28.
Compare resistivity with terminal pd.
[4 marks]
- ρ = RA/L
- ε = I(R+r) = V + Ir
- give one linked difference
29.
Compare terminal pd with potential divider.
[4 marks]
- ε = I(R+r) = V + Ir
- Vout = Vin × R2/(R1+R2)
- give one linked difference
30.
Compare potential divider with superconductivity.
[4 marks]
- Vout = Vin × R2/(R1+R2)
- zero resistivity below a critical temperature
- give one linked difference
31.
Apply your knowledge of Kirchhoff 1 to this situation: currents into a junction = currents out
[3 marks]
- currents into a junction = currents out
32.
Apply your knowledge of Kirchhoff 2 to this situation: sum of emfs = sum of pds around a loop
[3 marks]
- sum of emfs = sum of pds around a loop