Question:
Two parallel conductors a and b separated by distance \(d\) carry the same current. If the distance is doubled, the ratio of forces on conductor b before and after separation is:
Two parallel conductors a and b separated by distance \(d\) carry the same current. If the distance is doubled, the ratio of forces on conductor b before and after separation is:
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Force between parallel current-carrying wires varies inversely with separation distance.
Updated On: Jun 19, 2026
- 2:1
- 6:2
- 1:4
- 4:6
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The Correct Option is A
Solution and Explanation
Step 1: Force between parallel currents.
Force per unit length: \[ F \propto \frac{1}{d} \]
Step 2: Initial force.
\[ F_1 \propto \frac{1}{d} \]
Step 3: Final force after doubling distance.
\[ F_2 \propto \frac{1}{2d} \]
Step 4: Take ratio.
\[ F_1 : F_2 = \frac{1}{d} : \frac{1}{2d} \]
Step 5: Simplify ratio.
\[ F_1 : F_2 = 2 : 1 \]
Step 6: Final conclusion.
Thus, ratio is: \[ \boxed{2:1} \]
Force per unit length: \[ F \propto \frac{1}{d} \]
Step 2: Initial force.
\[ F_1 \propto \frac{1}{d} \]
Step 3: Final force after doubling distance.
\[ F_2 \propto \frac{1}{2d} \]
Step 4: Take ratio.
\[ F_1 : F_2 = \frac{1}{d} : \frac{1}{2d} \]
Step 5: Simplify ratio.
\[ F_1 : F_2 = 2 : 1 \]
Step 6: Final conclusion.
Thus, ratio is: \[ \boxed{2:1} \]
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