PHYSICS · Multi-part · CBSE · Physics · Current Electricity · Current Electricity
Problem
A dc power supply is connected to a long, thin wire. A probe measures the current in the wire for 5.0 s. The measurement can be described verbally as follows:
• From t = 0 to t = 2.0 s, the current increases linearly from 0 A to 4.0 A.
• From t = 2.0 s to t = 5.0 s, the current remains steady at 4.0 A.
Answer the following questions without carrying out detailed arithmetic calculations.
(a) Describe, in words, a graphical method you could use to determine the total amount of charge that passes a cross-section of the wire during the 5.0 s interval.
(b) On qualitative axes of your own, sketch the expected shape of a graph of total charge q(t) versus time for 0 ≤ t ≤ 5.0 s. Label any key features and explain how you constructed the graph based on the given description of the current.
(c) Suppose a second experiment used the same supply voltage but produced a current that is everywhere twice as large as the values listed above. Explain how and why the graph of q(t) would change compared with your sketch in part (b).