A fuse in an electrical circuit is designed to: MCQ with Answer and Explanation

Explanation:
Equipotential surface has constant potential V everywhere. Work done W = qΔV; since ΔV = 0 along equipotential, W = 0. This holds for any path on the surface. Electric field is perpendicular to equipotential surfaces, so no work is done moving charge along them. Memory aid: 'Equipotential: ΔV=0 ⇒ W=0; field lines ⊥ equipotentials'. This electrostatics concept is frequently tested in competitive exams. Always link work to potential difference, not absolute potential; path independence is key for conservative fields.

Explanation:
A Venturimeter consists of a converging pipe, a narrow throat, and a diverging pipe. As fluid passes through the constricted throat, its velocity increases. According to Bernoulli's principle, this increase in kinetic energy must be accompanied by a strictly corresponding decrease in fluid pressure. By measuring this pressure difference, the flow rate can be precisely calculated.

Explanation:
This is based on the conservation of angular momentum (L = Iω), where 'I' is the moment of inertia and 'ω' is angular velocity. When the boy extends his arms, mass moves further from the axis of rotation, increasing his moment of inertia (I). Since 'L' is conserved, an increase in 'I' must result in a decrease in angular velocity (ω).