A changing magnetic field makes a current: generators and transformers

Answer Key - Grade 11 Science Worksheet - Challenge Me

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

1. 1.

   A line with 2 Ω of resistance carries 6000 W at 240 V. How much power is lost as heat in the line, Ari?

   1250 W
2. 2.

   A line with 3 Ω of resistance carries 12000 W at 6000 V. How much power is lost as heat in the line, Bo?

   12 W
3. 3.

   A line with 0.5 Ω of resistance carries 5000 W at 250 V. How much power is lost as heat in the line, Esme?

   200 W
4. 4.

   What lowers the power-line voltage before it reaches homes, Kira?

   • Longer, thinner wires along the way
   • Step-up transformers
   • Step-down transformers
5. 5.

   The same power is sent at 25 times the voltage. How does the heating loss in the line change, Luz?

   • It drops to 1/625
   • It rises 25 times
   • It drops to 1/25
6. 6.

   Milo says a step-up transformer gives out more energy than it takes in. Agree or disagree?

   • Agree: more volts means more energy
   • Agree: the extra turns make energy
   • Disagree: it can't add energy
7. 7.

   Noah says stepping up voltage with a transformer also steps up the current. Agree or disagree?

   • Agree: current follows the turns
   • Disagree: the current steps down
   • Agree: current and voltage rise together
8. 8.

   Pia says a magnet resting inside a coil makes a steady current. Agree or disagree?

   • Agree: the coil stores it
   • Agree: magnets push current along any wire
   • Disagree: the field must change
9. 9.

   How does a wireless charging pad charge a phone, Ren?

   • It sends charge through the air to the phone
   • Its changing field induces a current
   • It heats the battery
10. 10.

    A magnet falls slowly through a copper tube. Why, Tala?

    • Induced currents push back
    • Copper is magnetic and grabs it
    • Air in the tube holds it up