Immediately below this paragraph is a table
with links to the exam questions and answers for all three externals way back to 2013.
Focus on the exams for the last three years. Recognise the type of question e.g This is
a question about..... Know how you are going to set out your working when answering each type of question.
At 2:43 he talks about the corkscrew rule. We have taught this as the 'right hand grip' rule
At 4:27 he talks about Fleming's left hand rule. We have taught this as the right hand rule
11. magnetic flux
Magnetic flux refers to the quantity of magnetic field over a defined area. Its symbol is φ
and its unit is the weber, Wb.
12. magnetic flux density
Magnetic flux density (magnetic field value), B = φ/A, Wb m-2 or tesla, T.
13. Faraday's Law
ε is the induced voltage
A voltage is induced whenever there is a change in magnetic flux i.e whenever there is a change
in current in the coil or when there is a change in 'A' eg by rotating the coil inside a magnetic flux.
ε = -Δφ/Δt
Q2c from the 2022 exam
This is a 'Merit' question. The requirements for A and M are below
14. Lenz's Law
Whenever a voltage is induced, the direction of the voltage will act against the change in flux
that is inducing it.
15. the inductor
An inductor is a conducting wire coiled around a core, which is often an iron rod.
Q2b from the 2022 exam
This is an Achieved question. VL = 0. VR = 12V
16. voltage/time and current/time graphs for an inductor
Q2bi from the 2021 exam
This is an 'Excellence' question. The requirements for A, M, and E are below
Q2bii from the 2021 exam
This is a 'Merit' question. The requirements for A and M are below
17. time constant
Τ = L/R
Q2a from the 2022 exam
This is a 'Merit' question. The requirements for A and M are below
Q2a from the 2021 exam
This is a 'Merit' question. The requirements for A and M are below
18. self-inductance
Measures the capability of a coil to create magnetic flux through each of its turns. The
symbol is 'L' and the unit is the henry, H.
ε = -L(ΔI/Δt)
19. energy stored in an inductor
ε = 0.5LI2
While the current in a coil is increasing from 0 to I, the battery supplies the energy that is
needed for the work that is done against the magnetic field. The energy is converted to magnetic
potential energy and is stored in the coil.
Q2c from the 2021 exam
This is an 'Achieved' question
Q2d from the 2022 exam
This is an 'Excellence' question. The requirements for A, M, and E are below
At 4 minutes he talks about the left hand rule. We use the right hand rule, where the thumb points
in the direction of the current, the index finger points in the direction of the magnetic field, and
the second finger or palm points in the direction of the Lorenz force
It is really important that you understand how the same "loop of wire in a magnetic field" can be
used as a motor (if the magnetic field turns the coil) or as a generator (if the coil is turned by
some other external force)
21. The comparison of the energy dissipation in a resistor carrying direct current and
alternating current
22. peak and rms voltage and current
RMS is discussed at 20.45 in the video
23. voltage and current and their
phase relationship in LR and CR series circuits
24. phasor diagrams
25. reactance and
impedance and their frequency dependence in a series circuit
