Physics Electricity and Magnetism 5

Question 1

A solenoid has 1,000 turns, a length of 0.5 m, and a cross-sectional area of 0.01 m². What is its inductance? (μ₀ = 4π×10⁻⁷ H/m)

Accepted Answer

25.1 mH

Answer

L = μ₀N²A/l = 4π×10⁻⁷ × 10⁶ × 0.01 / 0.5 ≈ 25.1 mH.

Question 2

What is the equivalent capacitance of two capacitors, 4 μF and 12 μF, connected in series?

Accepted Answer

3 μF

Answer

1/C_eq = 1/4 + 1/12 = 3/12 + 1/12 = 4/12, so C_eq = 3 μF.

Question 3

When a conductor is placed in electrostatic equilibrium inside an external electric field, the electric field inside the conductor is:

Accepted Answer

Zero

Answer

Free charges redistribute until the internal field is canceled, resulting in zero net field inside the conductor.

Question 4

The power dissipated in a resistor R carrying current I is expressed as:

Accepted Answer

P = I²R

Answer

Power dissipated as heat in a resistor is P = I²R, derived from P = IV and V = IR.

Question 5

Two long parallel wires carry currents in the same direction. They will:

Accepted Answer

Attract each other

Answer

Parallel currents in the same direction create magnetic fields that pull the wires toward each other.

Physics Practice Test