If the number of turns per unit length of a long solenoid is doubled, how does its self-inductance change, assuming other dimensions stay the same?
Options

Question

If the number of turns per unit length of a long solenoid is doubled, how does its self-inductance change, assuming other dimensions stay the same?

G1 Physics · Accepted Answer

Step 1: Inductance of an ideal long solenoid is L = μ₀N²A/ℓ; with n=N/ℓ it becomes L = μ₀n²Aℓ. Step 2: At unchanged coil length and cross section, doubling turns per unit length doubles n. Step 3: Inductance increases by 2² = 4 times. Answer D. Final answer: (D) become four times.