Grade 11 · Science · Physics

11th grade Magnetic force on moving charges, and how motors work worksheet

6 printable versionsOn Level10 questions · answer keyFree · no account

When it’s done, scan the sheet with your phone and PencilGo marks it and picks the next one. Create a free account

Version

Magnetic force on moving charges, and how motors work

Grade 11 Science Worksheet

NameDate

Circle the best answer, or write your answer on the line.

A wire with 0.1 m in a 0.5 T field carries 2 A, at 30° to the field lines. What force acts on it, to 0.01 N, Ari?
A wire with 0.2 m in a 0.4 T field carries 3 A, at 90° to the field lines. What force acts on it, to 0.01 N, Bo?
A wire with 0.2 m in a 0.6 T field carries 2.5 A, at 60° to the field lines. What force acts on it, to 0.01 N, Esme?
4.
Using the table, how are the force and the current related, Kira?
- Twice the current, 4 times the force
- They aren't related
- Twice the current, twice the force
5.
Using the table, the wire has 0.1 m in the field. What is the field strength, Luz?
Use the picture in question 4.
- 0.2 T
- 2 T
- 0.02 T
6.
A current-carrying wire is turned to lie along the field lines. What force does it feel, Milo?
- Its biggest force
- None
- Half its biggest force
7.
At what angle to the field lines does a wire feel the biggest force, Noah?
- 90°
- 0°, along the field
- 45°
8.
How is the force on a wire aimed compared with its current and the field, Pia?
- At right angles to both
- Along the field
- Along the current
9.
Which change makes a toy motor spin faster, Ren?
- Fewer turns on the coil
- A weaker magnet
- More current through the coil
10.
A motor coil is rewound with twice as many turns, at the same current. What happens to the force on each side, Zee?
- It doubles
- It halves
- It stays the same

Magnetic force on moving charges, and how motors work. Every version has 10 questions, and the answer key prints on the second page.

I can find the force on a wire, F = BIL sin θ. It is biggest at 90° to the field and zero along it, and it points at right angles to both the current and the field.
I can predict the direction: reversing the current or the field reverses the force, and reversing both keeps it.
I can explain a motor: forces push the coil's two sides opposite ways, the commutator flips the current every half turn, and the brushes carry current in. A coil of N turns gives F = NBIL. I know how to make a motor faster.
I can describe moving charges in a field: their paths curve, their speed doesn't change, and a still charge feels no force. Loudspeakers, fans and toy cars use these forces.

Standard: none (TX)

tesla (T): The unit of magnetic field strength

commutator: A split ring that reverses a motor coil's current every half turn

brushes: Contacts that press on the commutator to carry current in

motor: A device that turns electrical energy into motion using magnetic forces

θ (angle): The angle between the wire and the field lines

Your child left out the wire's length. The force on a wire is F = BIL: field × current × length in the field.

Your child used cosine. With θ between the wire and the field, the force uses sin θ: none when parallel, most at 90°.

Your child counted one turn. Each of the coil's N turns feels the force, so multiply by N.

What is the most common mistake with magnetic force on moving charges, and how motors work?

Your child left out the wire's length. The force on a wire is F = BIL: field × current × length in the field.

Are these 11th grade science worksheets free to print?

Yes. All 6 printable versions at each level are free to print, with the answer key, and no account is needed.

Every sheet you scan goes into your child’s record: dated, marked and ready for the year-end portfolio. Homeschool records