Answer: 200 cm.
- A 150 cm
- B 200 cm
- C 250 cm
- D 300 cm
Correct answer: B. 200 cm
Explanation: Terminal voltage of cell with 10 ohm shunt: V = E x R<sub>shunt</sub> / (r + R<sub>shunt</sub>) = 1.5 x 10/15 = 1 V. New length proportional: 300 x (1/1.5) = 200 cm.
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.