Magnetic field around a wire and inside a coil

Answer Key - Grade 11 Science Worksheet

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

1. 1.

   A solenoid has 400 turns over 0.2 m. What current gives a field of 5 mT inside, to 0.01 A, Bo? Use μ₀ = 4π × 10⁻⁷ T·m/A.

   1.99 A
2. 2.

   A solenoid has 1200 turns over 0.4 m. What current gives a field of 9 mT inside, to 0.01 A, Esme? Use μ₀ = 4π × 10⁻⁷ T·m/A.

   2.39 A
3. 3.

   A solenoid has 300 turns over 0.15 m. What current gives a field of 2 mT inside, to 0.01 A, Jun? Use μ₀ = 4π × 10⁻⁷ T·m/A.

   0.8 A
4. 4.

   The current in a long wire doubles. What happens to the field 3 cm away, Kira?

   • It doubles
   • It becomes 4 times as strong
   • It stays the same
5. 5.

   A point moves from 2 cm to 6 cm away from a long wire. What happens to the field, Luz?

   • It triples
   • It falls to a ninth
   • It falls to a third
6. 6.

   The field 4 cm from a long wire is 50 μT. What is it 1 cm from the wire, Milo?

   • 200 μT
   • 800 μT
   • 12.5 μT
7. 7.

   A solenoid's turns per meter are doubled at the same current. What happens to the field inside, Noah?

   • It stays the same, since the current did not change
   • It doubles
   • It halves
8. 8.

   A solenoid is made twice as long by adding turns at the same spacing, at the same current. What happens to the field inside, Pia?

   • It doubles, since there are twice as many turns
   • It halves, since it is twice as long
   • It stays the same
9. 9.

   Solenoid A has 1000 turns over 0.5 m; solenoid B has 1000 turns over 0.25 m. Both carry 2 A. Which has the stronger field inside, Ren?

   • A, since it is longer
   • B, with twice A's field
   • They are equal, with 1000 turns each
10. 10.

    Current 2 A, 20 μT; 4 A, 40 μT; 6 A, 60 μT; 8 A, 80 μT. Using the table, what would the field be at 4 cm for 8 A, Ari?

    • 20 μT
    • 40 μT
    • 160 μT