In given figure, an ammeter reads $5 \mathrm{~A}$ and voltmeter reads $40 \mathrm{~V}$. The actual value of…

In given figure, an ammeter reads $5 \mathrm{~A}$ and voltmeter reads $40 \mathrm{~V}$. The actual value of resistance $R$ is

1. $8 \Omega$
2. greater than $8 \Omega$
3. less than $8 \Omega$
4. $200 \Omega$

Solution

$ \text { Current in ammeter, } I=5 \mathrm{~A} $
We know that, voltmeter has a very high resistance. Hence, current flowing through voltmeter is very low. $ \begin{array}{ll} \therefore & 5=I_1+I_2 \Rightarrow I_1=5-I_2 \\ \text { As, } & I_2>0 \\ \therefore & I_1 < 5 \\ \Rightarrow & \frac{40}{R} < 5 \\ \Rightarrow & 8 < R \Rightarrow R>8 \Omega \end{array} $

Asked in: AP EAMCET 2020 (22 Sep Shift 1)

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