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CUET · PHYSICS · PYQ PAPER 2023

Resistance R1 is with 10 \(\Omega\) resistance in series and is in the first gap of meter bridge with R2 in the second gap. The balance point is at 50 cm. When the 10 \(\Omega\) resistance is removed then the balance point shifts to 40 cm. What is the value of R1?

  1. A 60 \(\Omega\)
  2. B 40 \(\Omega\)
  3. C 20 \(\Omega\)
  4. D 10 \(\Omega\)
Verified Solution

Answer & Solution

Correct Answer

(C) 20 \(\Omega\)

Step-by-step Solution

Detailed explanation

\(\frac{R_1 + 10}{R_2} = \frac{50}{100 - 50} \) \(R_1 + 10 = R_2\) (1) \(\frac{R_1}{R_2} = \frac{40}{100 - 40}\) \(3R_1 = 2R_2\) (2) \(3R_1 = 2(R_1 + 10)\) \(3R_1 = 2R_1 + 20\) \(R_1 = 20 \, \Omega\)