An electric lighting load is connected to a 110 V DC voltage source, which consumes a current of 25 A.

An electric lighting load is connected to a 110 V DC voltage source, which consumes a current of 25 A. What is the voltage loss in the supply wires if the load resistance is 4.2 Ohm?

1. Determine the voltage drop across the lamp, based on Ohm’s law for a section of the circuit:

Ul = Il * Rl = 4.2 * 25 = 105 V

2. Find the voltage loss in the wires using the regularities of the second Kirchhoff’s law for direct current circuits:

Upr = U – Ul = 110 – 105 = 5 V

Answer: 5V