In modern household wiring, a 'fuse' has largely been replaced by which device that performs the same safety function but can be reset? MCQ with Answer and Explanation
In modern household wiring, a 'fuse' has largely been replaced by which device that performs the same safety function but can be reset?
A. Rectifier
B. MCB (Miniature Circuit Breaker)
C. Capacitor
D. Inverter
Answer: Option B
Solution (By JKExamLibrary)
A Miniature Circuit Breaker (MCB) serves the same safety function as a fuse: breaking the circuit during an overload or short circuit. However, unlike a fuse wire that melts and must be physically replaced, an MCB contains an electromechanical mechanism that trips the switch. It can simply be switched back on to restore power.
Explanation:
Free fall: h = ½gt² ⇒ t = √(2h/g). Thus t ∝ √h. If h' = 4h, t' = √(4h/g) = 2√(h/g) = 2t. Time doubles when height quadruples. Memory aid: 'Free fall time: t ∝ √h; quadruple height ⇒ double time'. This kinematics proportional reasoning problem is frequently tested in competitive exams. Always derive the proportionality from fundamental equations; avoid assuming linear relationships for non-linear motion.
Explanation:
Tension is towards centre, displacement is tangential (velocity). Force perpendicular to displacement, cos90°=0, work zero. Centripetal force does no work, doesn't change speed.
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