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Lesson: Magnetic Field Energy

Sample Question Videos

Worksheet • 6 Questions • 1 Video

Q1:

A rectangular toroid has 2 000 windings around its core and the core has a height of 0.10 m. The toroid has a self-inductance of 0.040 H. What is the current through the toroid when the energy in its magnetic field is 2 . 0 × 1 0 6 J?

Q2:

A 10-H inductor carries a current of 2 0 × 1 0 3 mA. Calculate how much ice at 0 . 0 C could be melted by the energy stored in the magnetic field of the inductor. Use a value of 334 J/g for the latent heat of fusion of ice.

Q3:

There is a current of 1.2 A in a coaxial cable whose outer radius is five times its inner radius. The copper in the coaxial cable has a magnetic permeability 𝜇 = 1 . 2 6 × 1 0 / H m . What is the magnetic field energy stored in a 3.0-m length of the cable?

  • A 7 . 0 × 1 0 J
  • B 8 . 5 × 1 0 J
  • C 5 . 0 × 1 0 J
  • D 6 . 2 × 1 0 J
  • E 5 . 5 × 1 0 J

Q4:

At the instant a current of 0.50 A is flowing through a coil of wire, the energy stored in its magnetic field is 8 . 0 × 1 0 3 J. What is the self-inductance of the coil?

Q5:

A coil with a self-inductance of 5.0 H and a resistance of 200 Ω carries a steady current of 3.0 A. What is the energy stored in the magnetic field of the coil?

Q6:

A 7 0 0 0 µF capacitor is charged to 200 V and then quickly connected to a 70.0 mH inductor.

Determine the maximum energy stored in the magnetic field of the inductor.

Determine the peak value of the current.

Determine the frequency of oscillation of the circuit.

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