In a metre bridge [Fig], the gaps are closed by two resistances P and Q and the balance point is obtained
at 40 cm. When Q is shunted by resistance of 10 $Ω$ , the balance point shifts to 50 cm. The values of P and Q are

Question

In a metre bridge [Fig], the gaps are closed by two resistances P and Q and the balance point is obtained

at 40 cm. When Q is shunted by resistance of 10 $Ω$ , the balance point shifts to 50 cm. The values of P and Q are

Infinity Learn · Accepted Answer

For the balance of metre $$bridgePQ=RS=4060=23or$$ $$P=23Q$$……….(1)When$$ Q is shunted by a resistance of $$10$$ Ω then net resistance in this gap should be a parallel combination of Q and $$10$$ Ω resistance i.e., $$10Q$$ $$/10$$ $$+Q).Now the balance shifts to $$50$$ cm i.e., R $$=$$ $$50cm$$ and S $$=$$ $$50$$ cm. In this caseP[$$10Q/(10+Q)$$]$$=5050=1$$……..(2)Substituting$$ the value of  P from eq. $$(1) in eq. (2), we $$get(2/3)Q$$[$$10Q/(10+Q)$$]$$=1Solving$$ we get $$Q=5$$ΩFrom eq. (1),  $$P=23$$×$$5=103$$Ω

In a metre bridge [Fig], the gaps are closed by two resistances P and Q and the balance point is obtained
at 40 cm. When Q is shunted by resistance of 10 $Ω$ , the balance point shifts to 50 cm. The values of P and Q are

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In a metre bridge [Fig], the gaps are closed by two resistances P and Q and the balance point is obtained at 40 cm. When Q is shunted by resistance of 10 Ω, the balance point shifts to 50 cm. The values of P and Q are

Remember concepts with our Masterclasses.

Ready to Test Your Skills?

free study material

In a metre bridge [Fig], the gaps are closed by two resistances P and Q and the balance point is obtained
at 40 cm. When Q is shunted by resistance of 10 $Ω$ , the balance point shifts to 50 cm. The values of P and Q are