A 6 V battery is connected to a 3 Ω resistor. Current is MCQ with Answer and Explanation
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Question #1
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If the kinetic energy of a body is increased by 300%, its momentum will increase by:
Correct Answer: Option D
Explanation:
The relationship between kinetic energy (K) and momentum (p) is K = p² / 2m. If K is increased by 300%, the new kinetic energy K' = K + 3K = 4K. Since p = √(2mK), the new momentum p' = √(2m × 4K) = 2√(2mK) = 2p. The momentum has doubled. Percentage increase = [(2p - p)/p] × 100 = 100%.
The relationship between kinetic energy (K) and momentum (p) is K = p² / 2m. If K is increased by 300%, the new kinetic energy K' = K + 3K = 4K. Since p = √(2mK), the new momentum p' = √(2m × 4K) = 2√(2mK) = 2p. The momentum has doubled. Percentage increase = [(2p - p)/p] × 100 = 100%.
Question #2
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Convex lens in water: focal length:
Correct Answer: Option C
Explanation:
Lens maker: 1/f ∝ (n_rel - 1). In water, n_rel = n_glass/n_water ≈ 1.5/1.33 ≈ 1.13 < 1.5 (air). Smaller (n_rel-1) ⇒ larger f. Memory aid: 'Lens in denser medium: reduced power ⇒ longer focal length'. Optics application frequently tested in competitive exams.
Lens maker: 1/f ∝ (n_rel - 1). In water, n_rel = n_glass/n_water ≈ 1.5/1.33 ≈ 1.13 < 1.5 (air). Smaller (n_rel-1) ⇒ larger f. Memory aid: 'Lens in denser medium: reduced power ⇒ longer focal length'. Optics application frequently tested in competitive exams.
Question #3
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A ball of mass 0.5 kg moving at 4 m/s strikes a wall and rebounds at same speed. Impulse imparted is
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