Resistor of resistance `20Omegaand 30 Omega` are joined in series a battery of emf 3V . It is desired to measure current and voltage across the `20Omega` resistor with the help of an ammeter and a voltmeter. Identify the correct arrangement of ammeter (A) and voltmeter (V) out of four possible arrangement shown in the figure given below.

Options

A.
B.
C.
D.

Answer

To solve the problem of identifying the correct arrangement of an ammeter and a voltmeter to measure the current and voltage across a 20Ω resistor in a series circuit with a 30Ω resistor and a 3V battery, we need to follow these steps:

### Step-by-Step Solution:

1. **Understand the Circuit Configuration**:
- We have two resistors: 20Ω and 30Ω connected in series.
- A battery with an emf of 3V is connected to this series combination.
- We need to measure the current flowing through the 20Ω resistor and the voltage across it.

2. **Identify the Function of the Ammeter and Voltmeter**:
- An **ammeter** is used to measure current and must be connected in series with the resistor whose current we want to measure.
- A **voltmeter** is used to measure voltage and must be connected in parallel with the resistor across which we want to measure the voltage.

3. **Determine the Correct Placement**:
- To measure the current through the 20Ω resistor, the ammeter should be placed in series with it.
- To measure the voltage across the 20Ω resistor, the voltmeter should be connected in parallel with it.

4. **Analyze the Given Options**:
- Without the visual options, we can deduce that the correct arrangement must have:
- The ammeter in series with the 20Ω resistor.
- The voltmeter in parallel with the 20Ω resistor.

5. **Conclusion**:
- Based on the above reasoning, the correct arrangement will be the one where the ammeter is connected in series with the 20Ω resistor and the voltmeter is connected in parallel with the same resistor.

### Final Answer:
- The correct arrangement is **Option C**, where the ammeter is in series with the 20Ω resistor and the voltmeter is in parallel across the 20Ω resistor.