Magnetic force on moving charges, and how motors work
Grade 11 Science Worksheet - Building Confidence
Circle the best answer, or write your answer on the line.
A wire carries 3 A across a 0.5 T magnetic field, with 0.1 m of it in the field. What force acts on it, Ari?
A wire carries 4 A across a 0.2 T magnetic field, with 0.3 m of it in the field. What force acts on it, Bo?
A wire carries 1.5 A across a 0.8 T magnetic field, with 0.4 m of it in the field. What force acts on it, Esme?
Read this first
Field-line diagram (example data)
a wire sits between a magnet's north pole on the left and south pole on the right, so the field points to the right. The current in the wire flows out of the page, and a force arrow on the wire points up.
In the diagram, which way does the force on the wire point, Jun?
- Up
- Out of the page
- To the right, along the field
In the diagram, the current is reversed to flow into the page. Which way is the force now, Kira?
- To the left
- Down
- Still up
In the diagram, both the current and the magnet are reversed. Which way is the force, Luz?
- There is no force
- Down
- Still up
What does the split-ring commutator in a simple motor do, Noah?
- Stores the battery's charge
- Makes the magnet stronger
- Flips the current each half turn
What energy change does an electric motor make, Ren?
- Kinetic to electrical
- Light to electrical
- Electrical to kinetic
Why does a running motor get warm, Tala?
- Some energy becomes heat
- Magnets give off heat
- The commutator makes new energy
If the shaft of a small motor is spun by hand, what can the motor do, Zee?
- Nothing, since it needs a battery
- Make a small current, like a generator
- Turn into a magnet