Science · Circuits
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Secondary 1 · Science · Topic Drill

Electric Circuits

Switches · Series · Parallel · Current
16 questions · interactive diagrams · self-marked
⚡ Switches Series Parallel Current
⚡
Section A

Open & Closed Switches

Circuits need a complete loop. Current (moving charge) can only flow when there is an unbroken path from the battery's positive terminal, through the components, and back to the negative terminal. A switch controls this loop — open it and you break the path; close it and the path is complete.
Try it — click the switch to open or close it
+ − CELL SW ▸ click L1
Circuit: OPEN  |  Bulb L1: OFF
S1
The switch in the circuit above is open. What happens to bulb L1?
1 mark
A
It does not light up
B
It lights up dimly
C
It lights up at full brightness
D
It flashes on and off
S2
The switch is now closed. What happens to bulb L1?
1 mark
A
It still does not light up
B
The battery explodes
C
It lights up
D
The battery runs out instantly
S3
What does an open switch do to the electric circuit?
2 marks
A
It increases the voltage of the battery
B
It breaks the circuit and stops current from flowing
C
It makes the bulb glow brighter
D
It reverses the direction of current flow
🔗
Section B

Series Circuits

Series circuit — all components are connected in a single loop. Current follows one path only. If anything breaks the loop (open switch, broken bulb), all components stop working. The same current flows through every component.
Series circuit — click SW1 or SW2 to toggle each switch independently
+ − CELL SW1 ▸ SW2 ▸ L1
SW1: OPEN  |  SW2: OPEN  |  Bulb: OFF
S4
In the series circuit above, both SW1 and SW2 are closed. What happens to bulb L1?
1 mark
A
L1 flickers
B
L1 does not light up
C
L1 lights up
D
L1 lights up then goes out
S5
SW1 is open, SW2 is closed. What happens to bulb L1?
2 marks
A
L1 lights up because SW2 is closed
B
L1 lights up dimly
C
L1 lights up because the current bypasses SW1
D
L1 does not light up — one open switch breaks the whole series loop
S6
A series circuit has two bulbs, L1 and L2. Bulb L1 is removed from its socket. What happens to L2?
2 marks
A
L2 stays on at full brightness
B
L2 goes out
C
L2 glows brighter
D
L2 glows dimmer
S7
Three identical bulbs are connected in series to a battery. Compared to a single bulb on the same battery, each bulb in the series chain will be…
1 mark
A
Dimmer
B
The same brightness
C
Brighter
D
Off
⑂
Section C

Parallel Circuits

Parallel circuit — components are connected across separate branches between the same two nodes. Current can take multiple paths. Each branch is independent: switching off one branch does not affect the others. This is how household wiring works.
Parallel circuit — click SW1 or SW2 to toggle each branch independently
+ − CELL SW1 ▸ L1 SW2 ▸ L2
L1: OFF  |  L2: OFF
S8
In the parallel circuit above, SW1 is open and SW2 is closed. Which bulbs light up?
2 marks
A
Both L1 and L2 light up
B
Only L1 lights up
C
Only L2 lights up
D
Neither L1 nor L2 lights up
S9
Both switches are closed. Bulb L1 burns out (breaks its filament, creating a gap). What happens to L2?
2 marks
A
L2 stays on
B
L2 also goes out
C
L2 glows dimmer
D
L2 glows brighter
S10
Why is parallel wiring used in homes rather than series wiring?
1 mark
A
Each appliance works independently and gets full voltage
B
Parallel wiring uses less wire
C
Parallel wiring is cheaper to install
D
Parallel wiring prevents short circuits
S11
Three identical bulbs are wired in parallel to a battery. Compared to a single bulb on the same battery, each bulb in the parallel group will be…
1 mark
A
Dimmer, because voltage is shared
B
The same brightness
C
Brighter
D
Off
🔋
Section D

Current, Voltage & Resistance

Key quantities: Voltage (V) — the "push" provided by the battery, measured in volts (V). Current (I) — the flow of electric charge around the circuit, measured in amperes (A). Resistance (R) — how much a component opposes current, measured in ohms (Ω). These are related by Ohm's Law: V = I × R.
S12
What component in a circuit provides the "push" (voltage) that drives current around the loop?
1 mark
A
Resistor
B
Battery (cell)
C
Switch
D
Bulb
S13
What unit is used to measure electric current?
1 mark
A
Volts (V)
B
Ohms (Ω)
C
Watts (W)
D
Amperes (A)
S14
A resistor is added in series to a circuit. Using the relationship V = I × R, what happens to the current if resistance increases while voltage stays the same?
2 marks
A
Current increases
B
Current stays the same
C
Current decreases
D
Voltage decreases
⭐
Section E

Challenge Questions

S15 ⭐
Challenge: A circuit has a 6 V battery connected to two resistors in series: R1 = 1 Ω and R2 = 2 Ω. Using V = I × Rtotal, what is the current flowing in the circuit?
3 marks
A (amperes)
S16 ⭐
Challenge: In a parallel circuit with two branches, branch A has a resistance of 6 Ω and branch B has a resistance of 3 Ω. The battery voltage is 6 V. Which branch carries MORE current, and how much more?
3 marks
A
Branch A carries more current (2 A vs 1 A)
B
Both branches carry the same current (1 A each)
C
Branch B carries more current — 3 A vs 1 A in branch A
D
Branch B carries more current — 2 A vs 1 A in branch A
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