DSE Physics: Electricity and Magnetism — Tutor Lesson Plan (V = IR, series, parallel)

2026-10-27

Tutor lesson-prep guides · Secondary physics

Most circuit marks are lost before any arithmetic, because students cannot see which resistors are in series. Draw the equivalent circuit first, then calculate.

Objectives — the student can apply V = IR, reduce series and parallel networks, compute power with P = VI, and explain electromagnetic induction.

01 Prerequisites (3-minute check)

If any of these fails, fix it before the lesson starts.

Skill	Quick check	Pass mark
Current	Unit and conventional direction	Ampere; positive to negative
Fractions	Work out 1/6 + 1/3	1/2
Energy	What is one watt?	1 J/s

02 Lesson flow (60 minutes)

Time	Stage	Tutor does	Student does
0-10 min	Three quantities	How V, I and R relate	Write V = IR
10-24 min	Ohm law	12 V across 4 ohm	Three questions
24-40 min	Series and parallel	Add, or add reciprocals	Reduce two circuits
40-52 min	Power and induction	P = VI; changing flux makes current	Two questions
52-57 min	Format	Draw the equivalent circuit first	Redraw one
57-60 min	Exit check	Three questions marked	Finish alone

03 Teaching script (read it out)

Scene 1: Three quantities, one equation

12 V across 4 ohm gives 3 A.
The same circuit dissipates P = VI = 36 W, also written I squared R.

Student computes the voltage across 6 ohm carrying 2 A: 12 V.

Scene 2: Series adds, parallel adds reciprocals

Series: 2 + 4 = 6 ohm with the same current everywhere.
Parallel: 1/6 + 1/3 = 1/2, so 2 ohm, with the same voltage across each branch.

Student draws 6 ohm and 3 ohm parallel as a single 2 ohm resistor.

Scene 3: Electricity and magnetism are one effect

A current makes a magnetic field; a changing field induces an emf in a conductor.
A generator turns motion into electricity; a motor turns electricity into motion.

Note: Lenz law says the induced current opposes the change.

04 Question types and worked steps

Type	Example	Steps	Answer
Current	12 V, 4 ohm	I = V/R	3 A
Series total	2 ohm and 4 ohm	Add	6 ohm
Parallel total	6 ohm and 3 ohm	Add reciprocals	2 ohm
Power	12 V, 3 A	P = VI	36 W

Sanity check (teach this): A series total is larger than its largest resistor; a parallel total is smaller than its smallest. If not, the arithmetic is wrong.

05 Independent practice (3 questions)

Question	Answer	What to watch
Voltage across 6 ohm at 2 A	12 V	V = IR
2 ohm parallel with 3 ohm	1.2 ohm	Reciprocals sum to 5/6
12 V at 3 A	36 W	P = VI

06 Common mistakes and what to say

Mistake	Student writes	Say this
Series and parallel mixed	adds parallel resistances	Parallel uses reciprocals and is smaller.
V and I swapped	V = I/R	V = IR, so I = V/R.
Wrong power formula	P = V/R	P = VI, I squared R, or V squared over R.
No equivalent circuit	substitutes straight away	Redraw first.

07 Homework (paper, section and question numbers)

Secondary physics chapter index — Use the three questions on this page

08 Exit check (last 5 minutes)

Question	Answer	Decision
Voltage across 6 ohm at 2 A	12 V	All right: move to waves
2 ohm parallel 3 ohm	1.2 ohm	One wrong: re-teach parallel
12 V at 3 A	36 W	Two wrong: repeat scene 2

09 Tutor FAQ

How many formulas?

Two, V = IR and P = VI; the rest follow.

Internal resistance?

Yes for DSE, but stabilise the ideal case first.

How to remember induction?

No change, no current.

Find a tutor — free

A TutorZone lesson-prep guide. Written by the TutorZone team; questions and lesson flow are original and are not taken from any school or publisher material.