If the distance between two charges is doubled, the electrostatic force between them will become:
A. Four times
B. Double
C. One-fourth
D. Half
Answer: Option C
Solution (By JKSSB Mock Tests)
According to Coulomb's Law, the electrostatic force (F) between two point charges is inversely proportional to the square of the distance (r) between them (F ∝ 1/r²). If the distance is doubled (r becomes 2r), the new force F' ∝ 1/(2r)² = 1/4r². Thus, the force becomes one-fourth of its original value.
Explanation:
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.
Explanation:
Power negative means concave lens. f = 1/P (in metre) = 1/(-2.5) = -0.4 m = -40 cm. So concave lens of focal length 40 cm. Focal length negative for concave.
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