Electromotive force of primary cell is 2.4V. What is the internal resistance if cell is short circuited and current become 4A.

Options

A. `1.2Omega`
B. `60Omega`
C. `0.6Omega`
D. `4Omega`

Explanation

To solve the problem, we need to determine the internal resistance of a primary cell when it is short-circuited, given that the electromotive force (EMF) of the cell is 2.4 V and the current flowing through the circuit is 4 A.

### Step-by-step Solution:

1. **Understand the Concept**: When a cell is short-circuited, the voltage across the terminals of the cell (V) becomes 0 V. The electromotive force (E) of the cell remains at 2.4 V.

2. **Use the Formula**: The relationship between EMF (E), current (I), internal resistance (r), and terminal voltage (V) can be expressed as:
\[ E = V + I \cdot r \]
Since the cell is short-circuited, we know that \( V = 0 \). Therefore, the equation simplifies to:
\[ E = I \cdot r \]

3. **Substitute Known Values**: We know:
- \( E = 2.4 \, \text{V} \)
- \( I = 4 \, \text{A} \)

Substituting these values into the equation gives:
\[ 2.4 = 4 \cdot r \]

4. **Solve for Internal Resistance (r)**: Rearranging the equation to solve for r:
\[ r = \frac{2.4}{4} \]

5. **Calculate the Value**: Performing the division:
\[ r = 0.6 \, \Omega \]

### Final Answer:
The internal resistance of the cell is \( 0.6 \, \Omega \).

---