Grade 9 · Science · Unit 7 of 10
Static Electricity
Charges, conductors and insulators
What your child practises
Positive and negative charges and the particles behind them, charging by friction, contact and induction, conductors and insulators, and electrical safety in a thunderstorm.
Alberta Curriculum learning outcome: Unit D: Electrical Principles and Technologies · static electricity, conductors and insulators
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
Why do lightning rods have a wire to the ground?
- To stop thunder
- To store the charge in the rod
- To attract more clouds
- To carry the electric charge safely into the Earth
Show answer
To carry the electric charge safely into the Earth
Hint: Grounding gives charge a safe path.
Question 2
A plastic rod is rubbed with wool and becomes negatively charged. What happened?
- New charges were created
- Protons moved from the wool to the rod
- Electrons moved from the wool to the rod
- Electrons moved from the rod to the wool
Show answer
Electrons moved from the wool to the rod
Hint: The wool lost electrons, so it is positive. Charge is moved, not created.
Question 3
An object that loses electrons becomes…
- lighter than air
- positively charged
- negatively charged
- neutral
Show answer
positively charged
Hint: Fewer electrons than protons gives a net positive charge.
Question 4
Which is the safest place during a thunderstorm?
- in a lake or pool
- in an open field
- inside a building or a hard-topped vehicle
- under a lone tree
Show answer
inside a building or a hard-topped vehicle
Hint: Lightning finds the tallest or most conductive path.
Question 5
An object has 37 protons and 31 electrons. Which describes it?
- neutral
- positively charged
- negatively charged
Show answer
positively charged
Hint: Fewer electrons than protons gives a net positive charge.
Question 6
An object that gains electrons becomes…
- negatively charged
- positively charged
- a different element
- neutral
Show answer
negatively charged
Hint: More electrons than protons gives a net negative charge.