Question

A voltmeter and a ammeter are connect in series to an ideal cell of emf E. the voltmeter reading is V, and the ammeter reading is I. Then
i. V < E

ii. The voltmeter resistance is V/I

iii. The potential difference across the ammeter is E V

iv. voltmeter resistance + ammeter resistance = E/I

Correct statements are

• A. i and ii
• B. ii and iii
• C. iii and iv
• D. all

Answer 1

The correct option is D all

(i) : Voltmeter reading $V=E-V_A$ $⟹V<E$

(ii) : Voltmeter resistance $R_V=\frac{V}{I}$ (from ohm's law)

(iii) : Potential difference across ammeter $V_A=E-V$

(iv) : Total resistance of the circuit $R_T=R_V+R_A$

Also from ohm's law, total resistance of the circuit $R_T=\frac{E}{I}$

$⟹$ $R_V+R_A=\frac{E}{I}$

Hence option D is correct.