Two cells P and Q each of emf 2.16 ~V are connected in series with a resistor of 19.6 . An ideal voltmeter reads 2 ~V , when connected across the cell P and 1.92 ~V when connected across the cell Q . The ratio of the internal resistances of

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Two cells P and Q each of emf 2.16 ~V are connected in series with a resistor of 19.6 . An ideal voltmeter reads 2 ~V , when connected across the cell P and 1.92 ~V when connected across the cell Q . The ratio of the internal resistances of the cell P and Q is

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Correct answer: B. 2 : 3

Emf of each cell =2.16 ~V Emf of circuit =4.32 ~V Current in circuit, I= 4.32 r₁+r₂+19.6 Now, using V=E-I r for both cells, we have For P, 2=2.16- 4.32 r₁ r₁+r₂+19.6 and For Q, 1.92=216- 4.32 r₂ r₁+r₂+19.6 So, we have, From Eqs. (i) and (ii), we get r₁: r₂=2: 3

Two cells P and Q each of emf 2.16 ~V are connected in series with a resistor of 19.6 . An ideal voltmeter reads 2 ~V , when connected across the cell P and 1.92 ~V when connected across the cell Q . The ratio of the internal resistances of the cell P and Q is

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