PHYSICS · Multi-part · CBSE · Physics · Current Electricity · Current Electricity
Problem
Two identical uniform resistance wires, each of resistance R = 4.0 Ω, are connected separately to ideal batteries A and B.
• Battery A provides a constant emf of 6.0 V.
• Battery B provides a constant emf of 9.0 V.
Assume the temperature of each wire remains constant and that the resistances do not change with current.
(a) Determine the steady current in the wire connected to Battery A.
(b) Determine the steady current in the wire connected to Battery B.
(c) Compare the magnitudes of the average drift speeds of free electrons in the two wires. State the numerical ratio vd,B/vd,A and explain your reasoning without introducing additional formulas beyond those you use in parts (a) and (b).
(d) If identical miniature light–emitting diodes (LEDs) replaced the wires and operated safely at either current, describe which LED would appear brighter, or if they would have equal brightness. Support your answer with quantitative or qualitative reasoning.