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A precision laboratory resistor with a coil of wire 1.50 cm in diameter and 4.00 cm long, and 500 turns. What is its self-inductance?

a) 2.25 x 10^-6 H
b) 3.14 x 10^-6 H
c) 4.50 x 10^-6 H
d) 6.28 x 10^-6 H

User Joyrex
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1 Answer

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Final answer:

The self-inductance of a precision laboratory resistor made of a coil of wire with a 1.50 cm diameter, 4.00 cm length, and 500 turns is approximately 2.25 x 10^-6 H, which matches option (a). This calculation uses the formula for the self-inductance of a long solenoid and includes the permeability of free space, number of turns, cross-sectional area, and length of the solenoid.

Step-by-step explanation:

Calculating the Self-Inductance

The formula for the self-inductance (L) of a long solenoid is given by:

L = (μ0 N2 A) / l

Where:

  • μ0 is the permeability of free space (4π x 10-7 H/m)
  • N is the number of turns (500 turns)
  • A is the cross-sectional area of the solenoid (πr2)
  • l is the length of the solenoid (4.00 cm = 0.04 m)

Given that the diameter (d) is 1.50 cm, the radius (r) is 0.75 cm = 0.0075 m:

A = πr2 = 3.14159 * (0.0075 m)2

L = (4π x 10-7 H/m * 5002 * π * (0.0075 m)2) / 0.04 m

Upon calculating, we find that the self-inductance of the coil is approximately 2.25 x 10-6 H, which corresponds to option (a).

User Repo
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