The force on a current-carrying conductor in a magnetic field is maximum when the conductor is MCQ with Answer and Explanation

The force on a current-carrying conductor in a magnetic field is maximum when the conductor is
A. At 45°
B. Perpendicular to field
C. Parallel to field
D. At 60°
Answer: Option B
Solution (By JKSSB Mock Tests)
F = BIL sinθ. Maximum when θ = 90° (sin90°=1), so perpendicular. Parallel (θ=0°) force zero. This is the motor effect, used in electric motor.

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Practice More Physics Questions

Question #1
Momentum conservation follows from:
A. Newton's second law
B. Energy conservation
C. Newton's first law
D. Newton's third law

Correct Answer: Option D


Explanation:
Internal forces cancel in pairs (third law), so net external force = 0 ⇒ dp/dt = 0 (second law) ⇒ momentum constant. Memory aid: 'Momentum conservation ⇔ no external force ⇔ action-reaction pairs'. Mechanics foundation frequently tested in competitive exams.

This question belongs to: Science Physics
Question #2
If X = a²b³/c², and percentage errors in a, b, c are 2% each, the maximum percentage error in X is
A. 12%
B. 8%
C. 14%
D. 10%

Correct Answer: Option C


Explanation:
ΔX/X = 2(Δa/a) + 3(Δb/b) + 2(Δc/c) = 2×2% + 3×2% + 2×2% = 4% + 6% + 4% = 14%. Always add absolute relative errors.

This question belongs to: Science Physics
Question #3
The frequency of a tuning fork is 512 Hz. It produces resonance in a closed organ pipe of length 16 cm (speed of sound 340 m/s). The pipe resonates in
A. Second overtone
B. End correction needed
C. Fundamental mode
D. First overtone

Correct Answer: Option C


Explanation:
For closed pipe, fundamental f = v/(4L) = 340/(4×0.16) = 340/0.64 ≈ 531 Hz, close to 512 Hz, slight difference due to end correction. So fundamental. Approx match, SSC type.

This question belongs to: Science Physics