Question

4.1.2 quiz: electricity
question 5 of 10
what happens to a circuits resistance (r), voltage (v), and current (i) when you change the thickness of the wire in the circuit?
a. r and i will also change, but v will remain constant.
b. r, v, and i will all remain constant.
c. r and v will also change, but i will remain constant.
d. v and i will also change, but r will remain constant.

Explanation:

• Resistance (\(R\)): The resistance of a wire is inversely proportional to its cross - sectional area (\(A\)) (thickness). The formula for resistance is \(R=

ho\frac{l}{A}\) (where \(
ho\) is resistivity and \(l\) is length). So, changing the thickness (area \(A\)) changes \(R\).

• Voltage (\(V\)): The voltage of the power source in a circuit (assuming a simple circuit with a single power source) is determined by the power source itself (e.g., a battery has a fixed electromotive force). So \(V\) remains constant.
• Current (\(I\)): Using Ohm's law \(V = IR\). Since \(V\) is constant and \(R\) changes, \(I=\frac{V}{R}\) will change.

Answer:

A. \(R\) and \(I\) will also change, but \(V\) will remain constant.