In a meter bridge experiment, the circuit diagram and the corresponding observation table are shown in figure. \begin{tabular}{ccc} Sl. No. & $\mathrm{R}(\Omega)$ & $l(\mathrm{~cm})$ \\ 1. & 1000 & 60 \\ 2. & 100 & 13 \\ 3. & 10 & 1.5 \\ 4. & 1 & 1.0 \end{tabular} Which of the readings is inconsistent?

JEE Main · 2019 · 10 Apr 2019 · Shift 1 · Current Electricity

In a meter bridge experiment, the circuit diagram and the corresponding observation table are shown in figure.

\begin{tabular}{ccc}
Sl. No. &

R (Ω)

l (cm)

\end{tabular}

Which of the readings is inconsistent?

Answer: (A)

In a metre bridge the unknown is

x = \frac{R ( 100 - ℓ )}{ℓ}

. The first three readings give

x = \frac{1000 \times 40}{60} \approx 667 Ω

x = \frac{100 \times 87}{13} \approx 669 Ω

and

x = \frac{10 \times 98.5}{1.5} \approx 656 Ω

, all clustering near

660 Ω

. The fourth gives

x = \frac{1 \times 99}{1} = 99 Ω

, wildly different from the rest, so that observation is the inconsistent one.

JEE Main · 2019 · 10 Apr 2019 · Shift 1 · Single correct option