Grade 9 Electric Current worksheet
from Gradelings · Name: ______________________
How to explain it
- Current is the flow of charge. Voltage is the push. Resistance slows the flow.
- Ohm’s law: V = I × R. Energy = power × time (E = P × t).
- Homes are wired in parallel so each device works on its own.
Example: A 60 W lamp runs for 4 hours. How many watt-hours does it use? E = P × t. 60 × 4 = 240. Answer: 240 Wh
Question 1
Two resistors, 6 Ω and 6 Ω, are connected in series. What is the total resistance?
answer boxΩ
12 Ω
Hint: In a series circuit the resistances add: 6 + 6 = 12 Ω.
Question 2
In a series circuit, if one bulb burns out…
- the battery stops
- nothing changes
- the other bulbs get brighter
- the other bulbs go out too
the other bulbs go out too
Hint: A series circuit has only one path, so a break stops all current.
Question 3
Why does a charged balloon stick to a wall?
- Opposite charges attract.
- The wall is a magnet.
- Air pushes it.
- Gravity pulls it.
Opposite charges attract.
Hint: The balloon's charge causes opposite charge to gather on the nearest part of the wall.
Question 4
In a parallel circuit, if one bulb burns out…
- the battery explodes
- all the bulbs go out
- the other bulbs stay lit
- current stops everywhere
the other bulbs stay lit
Hint: Parallel circuits have separate branches, so current still flows through the others.
Question 5
A circuit has a resistance of 10 Ω and a current of 2 A. What is the voltage in volts? (V = I × R)
answer boxV
20 V
Hint: V = I × R = 2 × 10 = 20 V.
Question 6
A device rated 180 W runs for 2 hours. How many watt-hours of energy does it use? (E = P × t)
answer boxWh
360 Wh
Hint: Energy = power × time = 180 × 2 = 360 Wh.
Question 7
Houses are wired in parallel because…
- it makes bulbs dimmer
- series circuits do not work
- it uses less metal
- each device can work independently on the full voltage
each device can work independently on the full voltage
Hint: Each branch gets the same voltage and can be turned off without affecting others.
Question 8
Resistance is measured in…
- volts (V)
- ohms (Ω)
- watts (W)
- amperes (A)
ohms (Ω)
Hint: Resistance opposes current flow and is measured in ohms.
Question 9
A battery supplies 9 V to a resistor of 3 Ω. What is the current in amperes? (I = V ÷ R)
answer boxA
3 A
Hint: I = V ÷ R = 9 ÷ 3 = 3 A.
Question 10
Two resistors, 6 Ω and 8 Ω, are connected in series. What is the total resistance?
answer boxΩ
14 Ω
Hint: In a series circuit the resistances add: 6 + 8 = 14 Ω.
Answer key
- 1. 12 Ω
- 2. the other bulbs go out too
- 3. Opposite charges attract.
- 4. the other bulbs stay lit
- 5. 20 V
- 6. 360 Wh
- 7. each device can work independently on the full voltage
- 8. ohms (Ω)
- 9. 3 A
- 10. 14 Ω
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