A metre bridge measures unknown resistance X against a 10 Ω standard. The null point is at the 52 cm mark; the end corrections at ends A and B are 1 cm and 2 cm respectively. If X = (10 + k/10) Ω, find k.
Physics · Mixed Chapter
JEE Mains

Question

A metre bridge measures unknown resistance X against a 10 Ω standard. The null point is at the 52 cm mark; the end corrections at ends A and B are 1 cm and 2 cm respectively. If X = (10 + k/10) Ω, find k.

Physics · Mixed Chapter

G1 Physics · Accepted Answer

Step 1 — Include end corrections: Measured left length = 52 cm and left correction = 1 cm, so effective left length = 53 cm. Measured right length = 100−52 = 48 cm and right correction = 2 cm, so effective right length = 50 cm. Step 2 — Metre-bridge balance: X/(10 Ω) = 53/50. Therefore X = 10×53/50 = 10.6 Ω. Step 3 — Read the required parameter: X = 10 + k/10 ⇒ 10.6 = 10 + k/10 ⇒ k = 6. Answer: 6.