QJEEM19Phbecd: JEE Main 2019 Physics - Class 12 JEEM19Phbecd Solution: In a Wheatstone bridge(see fig.), Resistances P and Q are…

Question

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In a Wheatstone bridge(see fig.), Resistances P and Q are approximately equal. When R = 400

Ω

, the bridge is balanced. On interchanging P and Q, the value of R, for balance, is 405

Ω

. The value of X is close to :

JEE Main 2019 (Online) 11th January Morning Slot Physics - Current Electricity Question 259 English

Accepted Answer

For a balanced bridge,

\frac{P}{Q} = \frac{400}{X}

......(i)

After interchanging P and Q,

\frac{Q}{P} = \frac{405}{X}

......(ii)

Multiplying equation (i) and (ii), we get

X² = 400

\times

405

\Rightarrow

X =

\sqrt{400 \times 405}

= 402.5

Ω

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