Question

An ammeter and a voltmeter are connected in series to an ideal battery of emf $E$. If the ammeter reads $I$ and voltmeter reads $V$, then.

• A. $V<\epsilon$
• B. The resistance of voltmeter is $V/I$
• C. P.D across the ammeter is $E-V$
• D. Ammeter and voltmeter have equivalent resistance $=E/I$

Answer 1

Answer: (A), (B), (C), (D)

The correct options are
A $V<\epsilon$
B The resistance of voltmeter is $V/I$
C P.D across the ammeter is $E-V$
D Ammeter and voltmeter have equivalent resistance $=E/I$

Here,

Ammeter and Voltmeter are connected in series with a battery of emf $E$,

Let us suppose resistance of Ammeter be $R_a$ and voltmeter be $R_v$,

And $I$ be current flowing in the circuit,

$E-I{R}_v-I{R}_a=0$. (1)

Now, $I{R}_v=\text{Reading of Voltmeter}\left(V\right)$

It is clear from the equation (1) that

$V<E$

Also,

$V=I{R}_v$

Then,

$R_v=\frac{V}{I}$

Also,

P..D across ammeter$=I{R}_a=E-I{R}_v=E-V$

Also,

Equivalent resistance of Ammeter and voltmeter$=R_a+R_v$

From equation 1,

$R_a+R_v=\frac{E}{I}$

Option $\text{A,B,C,D}$ is the correct answer