Identify the correct statements from the following for an electrical circuit.
(A) An ammeter of very low resistance is connected in series in the circuit.
(B) A voltmeter of high resistance is connected in series with a resistance in the circuit.
(C) A current I coming at a point P of a circuit, divides into 4 small currents flowing through different branches and all the currents again combine to give current I at the next point S of the circuit. The branches are in parallel.
(D) The internal resistance of the batteries can always be neglected.
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → (A) and (C) only
A meter must disturb the circuit as little as possible: an ammeter measures the current through an element, a voltmeter the potential difference across it.
(A) An ammeter of very low resistance is connected in series in the circuit. — Correct. The current to be measured must pass through it, and its low resistance hardly changes that current.
(B) A voltmeter of high resistance is connected in series with a resistance in the circuit. — Incorrect. A voltmeter is connected in parallel across the resistance; its high resistance makes it draw very little current.
(C) A current I coming at a point P of a circuit, divides into 4 small currents flowing through different branches and all the currents again combine to give current I at the next point S of the circuit. The branches are in parallel. — Correct. All four branches are joined between the same two points P and S, so they have the same potential difference across them; this is a parallel combination.
(D) The internal resistance of the batteries can always be neglected. — Incorrect. It can be neglected only when it is much smaller than the external resistance.