A student carries out meter bridge experiment in 2 ways as shown in figure 1 \& 2. In figure-1, he obtains the null point at $ℓ = 24 cm$ . In figure-2, he obtains the null point at $x = \frac{3}{7} m$ . If unknown resistance $R = 20Ω$ , what is the resistance of left strip $(R_{L})$ and right strip $R_{R}$ ?

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TestHub · Accepted Answer

​ 30 20 ​ = R R ​ + 7.6 R L ​ + 2.4 ​ ⇒ 20 R R ​ + 152 = 30 R L ​ + 72 ​ ⇒ 2 R R ​ + 8 = 3 R L ​ ​ 30 + R R ​ 20 + R L ​ ​ = 10 ( 1 − x ) 10 x ​ = 4 3 ​ ⇒ 80 + 4 R L ​ = 90 + 3 R R ​ ​ 2 × ( 3 R R ​ − 4 R L ​ = − 10 ) ​ − 3 × ( 2 R R ​ − 3 R L ​ = − 8 ) ​ ​ R L ​ = 4Ω ​ R R ​ = 2Ω. ​

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JEE Advanced 2027 (Class 12+)