Question

A meter bridge with resistance R₁ and R₂ connected in two gaps is balanced at 0.4m from zero end. If smaller resistance is connected in series with 10 Ω resistance, the balance point is shifted to 0.4m from the other end. The value of smaller resistance is-

• A. 40Ω
• B. 60Ω
• C. 20Ω
• D. 8Ω

Answer 1

Answer: (D)

8Ω

Answer 2

$\frac { \mathrm { R } _ { 1 } } { \mathrm { R } _ { 2 } } = \frac { 0.4 } { 0.6 } \Rightarrow \frac { \mathrm { R } _ { 1 } } { \mathrm { R } _ { 2 } } = \frac { 2 } { 3 }$

$\frac { \mathrm { R } _ { 1 } + 10 } { \mathrm { R } _ { 2 } } = \frac { 0.6 } { 0.4 } \Rightarrow \frac { \mathrm { R } _ { 1 } + 10 } { 3 / 2 \mathrm { R } _ { 1 } } = \frac { 3 } { 2 }$

∴ R₁ = 8Ω