1.
State what is meant by current.
[1 mark]
- flow of charge
JD SCIENCE
P3 Electricity and magnetism
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 potential difference.
[1 mark]
- work done per coulomb
3.
State what is meant by resistance.
[1 mark]
- how difficult it is for current to flow
4.
State what is meant by Ohm's law.
[1 mark]
- I is proportional to V at constant T
5.
State what is meant by a series circuit.
[1 mark]
- one loop
6.
State what is meant by a parallel circuit.
[1 mark]
- more than one loop
7.
State what is meant by electrical power.
[1 mark]
- P = VI = I²R = V²/R
8.
State what is meant by mains electricity.
[1 mark]
- a.c. 230 V, 50 Hz in the UK
9.
State what is meant by the national grid.
[1 mark]
- system of cables and transformers
10.
State what is meant by static electricity.
[1 mark]
- charge that builds on insulators
11.
Grace is asked about current in a OCR Physics paper.
(a) [2 marks]
- I = Q/t
(b) [3 marks]
- measured in amps, ammeter in series
12.
Grace is asked about potential difference in a OCR Physics paper.
(a) [2 marks]
- V = E/Q
(b) [3 marks]
- voltmeter in parallel
13.
Grace is asked about resistance in a OCR Physics paper.
(a) [2 marks]
- R = V/I
(b) [3 marks]
- ohms
14.
Grace is asked about Ohm's law in a OCR Physics paper.
(a) [2 marks]
- ohmic conductor
(b) [3 marks]
- straight I–V graph through origin
15.
Grace is asked about a series circuit in a OCR Physics paper.
(a) [2 marks]
- current the same, voltages add
(b) [3 marks]
- resistors add
16.
Grace is asked about a parallel circuit in a OCR Physics paper.
(a) [2 marks]
- voltage the same, currents add
(b) [3 marks]
- total R is less than the smallest
17.
Q = It. 2 A for 30 s
[3 marks]
- Final answer: 60 C
18.
R = V/I. 12 V, 0.25 A
[3 marks]
- Final answer: 48 Ω
19.
P = VI. 230 V, 2 A
[3 marks]
- Final answer: 460 W
20.
E = Pt. 2 kW for 0.5 h in kWh
[3 marks]
- Final answer: 1 kWh
21.
Two 4 Ω resistors in series
[3 marks]
- Final answer: 8 Ω
22.
Two 4 Ω resistors in parallel
[3 marks]
- Final answer: 2 Ω
23.
Grace carries out a OCR-style required practical linked to electricity. This is a typical OCR 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.
Grace carries out collecting valid data for electricity. This is a typical OCR 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.
Grace carries out drawing a graph for electricity. This is a typical OCR 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.
Grace carries out evaluating a method about electricity. This is a typical OCR 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 current with potential difference.
[4 marks]
- flow of charge
- work done per coulomb
- give one linked difference
28.
Compare potential difference with resistance.
[4 marks]
- work done per coulomb
- how difficult it is for current to flow
- give one linked difference
29.
Compare resistance with Ohm's law.
[4 marks]
- how difficult it is for current to flow
- I is proportional to V at constant T
- give one linked difference
30.
Compare Ohm's law with a series circuit.
[4 marks]
- I is proportional to V at constant T
- one loop
- give one linked difference
31.
Apply your knowledge of electrical power to this situation: energy per second
[3 marks]
- energy per second
32.
Apply your knowledge of mains electricity to this situation: live, neutral, earth
[3 marks]
- live, neutral, earth