Assertion: Acceleration in SHM is maximum at extremes. Reason: Restoring force ∝ displacement.
A. A false, R true
B. Both true, R doesn't explain A
C. A true, R false
D. Both true, R explains A
Answer: Option D
Solution (By JKSSB Mock Tests)
Assertion true: a = -ω²x, max at max |x|. Reason true: F = -kx (Hooke's law), and F = ma ⇒ a ∝ -x. Reason correctly explains why acceleration peaks at extremes. Memory tip: 'SHM: F ∝ -x ⇒ a ∝ -x'. Assertion-reason testing SHM fundamentals, frequently examined in competitive exams.
Explanation:
LEDs are highly efficient, converting ~80-90% of electrical energy into light, rest heat. Incandescent bulbs ~10% efficient. LED long life, low power. Blue LED Nobel prize 2014.
Explanation:
An electric iron contains a heating element (usually nichrome). When electric current passes through this high-resistance element, it produces heat according to Joule's law (H = I²Rt). An electric fan uses the magnetic effect (motor), a generator uses electromagnetic induction, and a transformer uses mutual induction.
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