- 2017:
The answer is (A) R/4.
When a wire is cut into four equal parts, the resistance of each part becomes R/4. When these parts are connected in parallel, the equivalent resistance of the combination becomes R/4 * 4 = R.
- 2016:
The answer is (C) 3 ohm.
When two resistors R1 and R2 are connected in parallel, the equivalent resistance is given by R = (R1 * R2) / (R1 + R2). In this case, R = (4 * 3) / (4 + 3) = 3 ohm.
- 2015:
The answer is (B) 40 ohm.
When a wire is stretched, its length increases but its cross-sectional area decreases. The resistance of a wire is inversely proportional to its cross-sectional area. So, when a wire is stretched, its resistance increases. In this case, the resistance of the wire increases from 10 ohm to 40 ohm.
