# Worksheet: Inductance

In this worksheet, we will practice calculating the self-inductance of a conducting loop and the mutual inductance of pair of conducting coils.

**Q1: **

A loop of wire has a potential difference of 1.2 V across it. The loop has a self-inductance of 125 mH. How much time is required for the loop to increase the current through it by 0.25 A?

**Q2: **

A transformer with an iron core has a primary coil that has 15 turns and a secondary coil that has also 15 turns. In a time of 0.25 s, a potential difference of 12 V is applied across the primary coil, inducing a potential difference of 12 V across the secondary coil. What is the change of the magnetic flux through the iron core?

**Q3: **

A transformer with an iron core has a primary coil that has 75 turns and a secondary coil that has also 75 turns. The coils have a mutual inductance of 15 H. The current in the primary coil increases the current in the secondary coil at a rate of 1.25 A/s. What is the potential difference across the coils?

**Q4: **

A loop of wire carries a current of 180 mA. The magnetic flux produced by the current is 0.77 Wb. What is the self-inductance of the loop?

- A 0.14 H
- B 2.6 H
- C 0.23 H
- D 4.3 H
- E 3.1 H

**Q5: **

A loop of wire has a self-inductance of 0.36 H. The current through the loop is 420 mA. What is the magnetic flux produced by the current?

- A 0.86 Wb
- B 0.78 Wb
- C 0.36 Wb
- D 1.2 Wb
- E 0.15 Wb

**Q6: **

A circuit is powered by a 7.5 V source. The circuit carries a steady current of 1.4 A and contains an inductor with a self-inductance of 680 mH. When the voltage source is disconnected from the circuit, how much time passes before the current in the circuit becomes zero?

- A 0.13 s
- B 0.25 s
- C 0.73 s
- D 0.19 s
- E 0.95 s

**Q7: **

The current induced in a loop of wire increases at 0.16 A/s. The loop has a self-inductance of 0.55 H. What is the potential difference across the loop?

**Q8: **

A transformer with an iron core has a primary coil with 25 turns and a secondary coil that also has 25 turns. The current in the primary coil increases the magnetic flux through the core by 0.15 Wb/s. The current in the secondary coil increases at 0.075 A/s. What is the mutual inductance of the coils?

**Q9: **

A transformer with an iron core has a primary coil with 45 turns and a secondary coil that also has 45 turns. The coils have a mutual inductance of 2.5 H. A current in the primary coil induces a potential difference of 2.2 V across the secondary coil in a time of 0.18 s. What is the current through the secondary coil after 0.18 s?