How to use this page
Each section is a short game or activity. Read the Instructions, try the task, then use Check or Show solution where available. Some games use calculations (with $V$, $I$, $N$, turns ratio, etc.) and some focus on observations and concepts.
Game 1: DC Motor — Label the parts
Instructions: Below are four parts of a simple DC motor. Match each label (A–D) to the correct part by clicking the option you think is right for each.
Schematic: coil in magnetic field, with contacts
A — where the coil is; B — reverses current every half turn; C — fixed contacts; D — magnet providing field
Game 2: DC Motor — Back EMF calculation
Instructions: In a DC motor, the coil rotates in a magnetic field and generates a back EMF $\mathcal{E}_\text{back}$ that opposes the supply voltage. The net voltage driving current through the coil resistance $R$ is $V_\text{supply} - \mathcal{E}_\text{back} = I R$. So $\mathcal{E}_\text{back} = V_\text{supply} - I R$. Use this to find the back EMF.
A motor is connected to 24 V and draws 2 A. The resistance of the coil is 3 Ω. What is the back EMF (in volts)?
Game 3: AC Generator vs DC Motor — Observations
Instructions: Choose the best answer for each question. Think about what output each device gives and what parts they use (commutator vs slip rings).
1. Which device uses slip rings (and not a commutator)?
2. Which device produces DC (direct current) at its output?
3. In a DC motor, what is the role of the commutator?
Game 4: Transformer — Step-up or Step-down?
Instructions: For an ideal transformer, $\dfrac{V_1}{V_2} = \dfrac{N_1}{N_2}$. If $V_2 > V_1$ (more turns on secondary) it is a step-up transformer; if $V_2 < V_1$ it is step-down. Say which type each is.
(a) Primary 200 turns, Secondary 800 turns.
(b) Primary 400 V, Secondary 100 V.
Game 5: Transformer — Voltage and turns
Instructions: Use the turns ratio: $\dfrac{V_1}{V_2} = \dfrac{N_1}{N_2}$. So $V_2 = V_1 \cdot \dfrac{N_2}{N_1}$. Find the missing value and type it below.
Primary: $N_1 = 500$ turns, $V_1 = 220\ \text{V}$. Secondary: $N_2 = 100$ turns. What is the secondary voltage $V_2$ (in volts)?
Game 6: Transformer — Power and current
Instructions: For an ideal transformer, power in ≈ power out: $P_1 = P_2$, so $V_1 I_1 = V_2 I_2$. Use this to find the unknown.
Primary: $V_1 = 200\ \text{V}$, $I_1 = 5\ \text{A}$. Secondary: $V_2 = 50\ \text{V}$. What is the secondary current $I_2$ (in amperes)?
Game 7: Where do we use which transformer?
Instructions: Match the application to the typical transformer type (step-up or step-down).
Power station sending electricity to the grid (increase voltage for long-distance transmission):
Wall adapter for a laptop (e.g. 230 V down to 19 V):