Answer: doubles.
- A halves
- B doubles
- C becomes four times
- D is unchanged
Correct answer: B. doubles
Explanation: I = neAv_d, so v<sub>d</sub> ∝ I; doubling the current doubles the drift velocity.
In series, the same current flows through both resistors; in parallel, the current splits between branches and the voltage across each resistor is the same.
Concept context
Ohm's law, resistors, Kirchhoff's laws, Wheatstone bridge, and cells.