A changing magnetic field makes a current: generators and transformers

Answer Key - Grade 11 Science Worksheet - Building Confidence

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

1. 1.

   A transformer's primary coil has 500 turns and gets 120 V. Its secondary coil has 50 turns. What voltage comes out, Ari?

   12 V
2. 2.

   A transformer's primary coil has 100 turns and gets 240 V. Its secondary coil has 25 turns. What voltage comes out, Bo?

   60 V
3. 3.

   A transformer's primary coil has 50 turns and gets 12 V. Its secondary coil has 200 turns. What voltage comes out, Esme?

   48 V
5. 4.

   In the diagram, the magnet is held still inside the coil. What does the needle show, Jun?

   • Zero
   • A swing left
   • A steady swing right
6. 5.

   In the diagram, the magnet is pulled back out. Which way does the needle swing, Kira?

   Use the picture in question 4.

   • Right, as before
   • Left
   • It doesn't move
7. 6.

   In the diagram, the magnet is pushed in faster. What happens to the needle's swing, Luz?

   Use the picture in question 4.

   • It swings the same
   • It swings farther
   • It swings less
8. 7.

   What makes a current flow in a coil with no battery, Milo?

   • A magnet resting beside it
   • A changing magnetic field through it
   • Warming the coil
9. 8.

   A coil with more turns is used with the same moving magnet. What happens to the current, Pia?

   • It gets smaller
   • It stays the same
   • It gets bigger
10. 9.

    A phone charger's transformer has fewer turns on its secondary coil. What does it do to the voltage, Tala?

    • Raises it
    • Leaves it the same
    • Lowers it
11. 10.

    Why won't a transformer work with a steady battery current, Zee?

    • The field must keep changing
    • Batteries are too weak
    • Transformers need heat