An ammeter and a voltmeter are joined in series to a cell. Their readings are `A` and `V` respectively. If a resistance is now joining parallel with the voltmeter. Then

Options

A. both `A` and `V `will increase
B. both and `V` will decreases
C. `A` will decrease, `V` will increase
D. `A` will increase, `V` will decrease

Explanation

To solve the problem, let’s analyze the situation step by step.

### Step 1: Understanding the Initial Setup
Initially, we have an ammeter and a voltmeter connected in series to a cell. The ammeter reads a current \( A \) and the voltmeter reads a voltage \( V \).

**Hint:** Remember that in a series circuit, the same current flows through all components.

### Step 2: Adding a Resistance in Parallel with the Voltmeter
Now, we introduce a resistance \( R_S \) in parallel with the voltmeter. This changes the circuit configuration.

**Hint:** When resistances are connected in parallel, the total or equivalent resistance decreases.

### Step 3: Effect on Total Resistance
Since the resistance \( R_S \) is added in parallel with the voltmeter, the equivalent resistance of the circuit decreases.

**Hint:** Use the formula for parallel resistances:
\[ \frac{1}{R_{net}} = \frac{1}{R_{V}} + \frac{1}{R_S} \]

### Step 4: Impact on Current
With the decrease in equivalent resistance, according to Ohm's Law (\( V = IR \)), the total current \( I \) flowing through the circuit will increase.

**Hint:** If the voltage of the cell remains constant and resistance decreases, current must increase.

### Step 5: Effect on Ammeter Reading
Since the ammeter measures the current flowing through the circuit, and we have established that the total current increases, the reading on the ammeter will also increase.

**Hint:** Remember that the ammeter reading is directly proportional to the total current in the circuit.

### Step 6: Effect on Voltmeter Reading
The voltmeter measures the voltage across itself. With the shunt resistance in parallel, some of the current will now flow through the shunt resistance instead of the voltmeter. This means that the current flowing through the voltmeter will decrease.

**Hint:** The voltmeter reading is affected by the current flowing through it and its resistance.

### Step 7: Conclusion
- The ammeter reading increases.
- The voltmeter reading decreases.

Thus, the correct option is:
- **Ammeter reading increases (A increases)**
- **Voltmeter reading decreases (V decreases)**

### Final Answer:
The ammeter reading will increase, and the voltmeter reading will decrease.