Question

To determine the equivalent resistance of two resistors when connected in series, a student arranged the circuit components as shown in the diagram. But he did not succeed to achieve the objective.
Which of the following mistakes has been committed by him in setting up the circuit?

A. position of voltmeter in incorrect
B. position of ammeter is incorrect
C. terminals of voltmeter are wrongly connected
D. terminals of ammeter are wrongly connected

Answer 1

Hint: The voltmeter is always connected in parallel such that positive of voltmeter is connected with positive of battery and negative of voltmeter with negative of battery. Ammeter is always connected in series with its positive with positive terminal of battery and negative with negative terminal of battery.

Complete step by step answer:

The ammeter and voltmeter into a circuit are always connected with the positive terminal of the battery. Here in figure 1. The voltmeter is connected with the positive terminal of the battery, which is correct.

Now look at the ammeter and observe that its positive terminal is connected with the negative terminal of the battery, which is incorrect that means this is the mistake that has taken place in the circuit due to which the student did not succeed to achieve the objective.
Now, for a student to achieve his goal, the polarity of the ammeter should be reversed. Now, the perfect circuit is shown in Figure 2.

So, the correct answer is “Option B”.

Note:
1. Ammeter is always connected in series into a circuit.
2. Voltmeter is always connected in parallel into a circuit.
3. The ammeter can be formed by connecting a series resistance with the galvanometer.
4. The voltmeter can be formed by connecting a parallel/ shunt resistance with the galvanometer.