Magnetic force on moving charges, and how motors work

Answer Key - Grade 11 Science Worksheet

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

1. 1.

   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?

   0.05 N
2. 2.

   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?

   0.24 N
4. 3.

   Using the table, how are the force and the current related, Kira?

   • They aren't related
   • Twice the current, twice the force
   • Twice the current, 4 times the force
5. 4.

   Using the table, the wire has 0.1 m in the field. What is the field strength, Luz?

   Use the picture in question 3.

   • 2 T
   • 0.02 T
   • 0.2 T
6. 5.

   A current-carrying wire is turned to lie along the field lines. What force does it feel, Milo?

   • Its biggest force
   • Half its biggest force
   • None
7. 6.

   At what angle to the field lines does a wire feel the biggest force, Noah?

   • 0°, along the field
   • 90°
   • 45°
8. 7.

   How is the force on a wire aimed compared with its current and the field, Pia?

   • Along the current
   • Along the field
   • At right angles to both
9. 8.

   Which change makes a toy motor spin faster, Ren?

   • A weaker magnet
   • Fewer turns on the coil
   • More current through the coil
10. 9.

    A toy motor's magnet is swapped for a stronger one. What happens, Tala?

    • It spins slower
    • It spins faster
    • It stops
11. 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 stays the same
    • It halves