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?

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

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

   Use the picture in question 4.

   • It doesn't move
   • Left
   • Right, as before
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 farther
   • It swings the same
   • It swings less
8. 7.

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

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

   A coil is moved past a magnet that stays still. Is a current made, Noah?

   • No: coils can't make current
   • No: the magnet must move
   • Yes: the field through the coil changes
10. 9.

    A transformer has 100 turns on its primary coil and 1000 on its secondary. What kind is it, Ren?

    • Step-down
    • Step-up
    • Neither
11. 10.

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

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