Grade 9 · Science · Unit 8 of 11
Electric Current
Circuits, Ohm's law and safety
What your child practises
Static electricity, current, voltage and resistance, solving V = I × R, series and parallel circuits, electrical safety, and electricity generation in BC.
New Brunswick Curriculum skill descriptor: Scientific Literacy: Sensemaking · electric current and circuits
Sample questions
A taste of this unit. In the app, questions change every time and get easier or harder to match your child.
Question 1
A switch turns off a circuit by…
- increasing the resistance to zero
- making the wire longer
- removing the battery's voltage
- creating a gap so current cannot flow
creating a gap so current cannot flow
Hint: An open switch makes an open circuit with no complete path.
Question 2
Two resistors, 3 Ω and 4 Ω, are connected in series. What is the total resistance?
answer boxΩ
7 Ω
Hint: In a series circuit the resistances add: 3 + 4 = 7 Ω.
Question 3
A device has 15 V across it and a current of 5 A. What is its resistance in ohms? (R = V ÷ I)
answer boxΩ
3 Ω
Hint: R = V ÷ I = 15 ÷ 5 = 3 Ω.
Question 4
What is static electricity?
- A flow of charge in a wire
- A kind of battery
- Heat in a circuit
- A build-up of electric charge on an object
A build-up of electric charge on an object
Hint: Rubbing materials together can transfer electrons, leaving objects charged.
Question 5
Why does a charged balloon stick to a wall?
- The wall is a magnet.
- Gravity pulls it.
- Opposite charges attract.
- Air pushes it.
Opposite charges attract.
Hint: The balloon's charge causes opposite charge to gather on the nearest part of the wall.
Question 6
In a circuit, voltage is…
- the energy given to each unit of charge (the push)
- the speed of light
- the flow of charge
- the opposition to flow
the energy given to each unit of charge (the push)
Hint: Voltage is measured in volts (V). A battery provides voltage.