Electric currents make magnetic fields

Answer Key - Grade 11 Science Worksheet - Building Confidence

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

1. 1.

   A long straight wire's field is 40 μT at 2 cm away. With the same current, what is it 4 cm away, Ari?

   20 μT
2. 2.

   A long straight wire's field is 60 μT at 1 cm away. With the same current, what is it 3 cm away, Bo?

   20 μT
3. 3.

   A long straight wire's field is 30 μT at 3 cm away. With the same current, what is it 2 cm away, Esme?

   45 μT

4. Read this first

   Use this

   Field-line diagram (example data): a straight wire carries current straight up out of the page. Circular field lines surround it, closer together near the wire. 4 compasses around the wire point along the circles, counterclockwise as seen from above.

6. 4.

   In the diagram, what shape are the field lines around the wire, Jun?

   • Lines along the wire
   • Circles
   • Straight lines out from the wire
7. 5.

   In the diagram, the current is reversed. What do the compasses do, Luz?

   Use the picture in question 4.

   • They point at the wire
   • They turn to point clockwise
   • They stay the same
8. 6.

   In the right-hand grip rule for a wire, what does the thumb point along, Milo?

   • The field lines
   • The current
   • North
9. 7.

   The current in the wire is switched off. What happens to its magnetic field, Pia?

   • It doubles
   • It disappears
   • It stays as it was
10. 8.

    A current flows through a coil of wire. What does its field look like, Ren?

    • No field outside the coil
    • Circles around one point
    • Like a bar magnet's field
11. 9.

    More turns are wound onto a coil with the same current. What happens to its field, Tala?

    • It gets weaker
    • It stays the same
    • It gets stronger
12. 10.

    An iron nail is put inside a coil carrying a current. What happens, Zee?

    • The field disappears
    • The field gets much stronger
    • The current stops