A transformer has 50 turns in the primary coil and 1000 turns in the secondary coil. If the primary voltage is 220V, what is the secondary voltage? MCQ with Answer and Explanation

Explanation:
Dioptre (D) = m⁻¹. Power = 1/f in metres. Convex positive, concave negative. Optometry uses dioptre.

Explanation:
Conservation of momentum: 0 = (0.02×200) + (5×v) => v = -4/5 = -0.8 m/s (magnitude 0.8 m/s).

Explanation:
Potentiometer sensitivity (ability to detect small EMF changes) increases with longer wire because potential gradient (V/cm) decreases, allowing finer measurement of balancing length. Sensitivity ∝ length of wire. Decreasing length (B) reduces sensitivity; increasing current (C) increases potential gradient, reducing sensitivity; thicker wire (D) reduces resistance but doesn't directly affect sensitivity if current adjusted. Memory tip: 'Longer potentiometer wire ⇒ smaller potential gradient ⇒ higher sensitivity'. This experimental physics concept is frequently tested in competitive exams. Always link sensitivity to potential gradient: smaller gradient allows detection of smaller voltage differences.