एक DC 2-तार फीडर 220 V के भेजने वाले छोर (sending-end) के वोल्टेज के साथ एक नियत लोड की आपूर्ति करता है। यदि संचारित शक्ति समान रखते हुए इस वोल्टेज को दोगुना कर दिया जाए, तो तांबे (copper) की बचत का प्रतिशत ज्ञात कीजिए।

Two inductors, each having a self-inductance of 1 H, are connected in parallel in such a way that their magnetic fluxes act in the same direction. If the mutual inductance is 0.5 H, find the equivalent inductance of the parallel connection.

A slide wire is used for the measurement of current in a circuit. The voltage across a standard resistance of 1.0 Ω is balanced at 75 cm. Find the magnitude of the current if a standard cell having an EMF of 2 V is balanced at 50 cm.