During an experiment with a metre bridge, the galvanometer shows a null point when the joceky is pressed at 40.0 cm using a standard resistance

Q: During an experiment with a metre bridge, the galvanometer shows a null point when the joceky is pressed at $40.0 \ cm$ using a standard resistance of $90 \ \Omega$, as shown in the figure. The least count of the scale used in the meter bridge is $1 \ mm$. The unknown resistance is:

c For balanced meter bridge $\frac{X}{R}=\frac{\ell}{(100-\ell)}$ $\frac{X}{40}=\frac{90}{60} \Rightarrow X=60 \Omega$ $X=R \frac{\ell}{(100-\ell)}$ $\frac{\Delta X}{X}=\frac{\Delta \ell}{\ell}+\frac{\Delta \ell}{100-\ell}=\frac{0.1}{40}+\frac{0.1}{60}$ $\Delta X=0.25$ $\text { so अत: } X=(60 \pm 0.25) \Omega$

SECTION - A [PHYSICS - MCQ]

GSEB - English Medium

During an experiment with a metre bridge, the galvanometer shows a null point when the joceky is pressed at $40.0 \ cm$ using a standard resistance of $90 \ \Omega$, as shown in the figure. The least count of the scale used in the meter bridge is $1 \ mm$. The unknown resistance is:

A$60 \pm 0.15 \ \Omega$
B$135 \pm 0.56 \ \Omega$
C$60 \pm 0.25 \ \Omega$
D$135 \pm 0.23 \ \Omega$

IIT 2014, Advanced

STD 11 Science
NEET
STD 12 - 3. current electricity
Physics

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