Primary and secondary coil of a transformer have 20 and 100 turns respectively. Primary coil is supplied with 220 V dc supply then voltage across secondary coil will be:

Options

A. 1100 V
B. 220 V
C. 11 V
D. 0 V

Explanation

To solve the problem, we need to use the transformer equation, which relates the voltages and the number of turns in the primary and secondary coils. The equation is given by:

\[ \frac{V_s}{V_p} = \frac{N_s}{N_p} \]

Where:
- \( V_s \) is the voltage across the secondary coil,
- \( V_p \) is the voltage across the primary coil,
- \( N_s \) is the number of turns in the secondary coil,
- \( N_p \) is the number of turns in the primary coil.

### Step-by-Step Solution:

1. **Identify the given values:**
- Number of turns in the primary coil, \( N_p = 20 \)
- Number of turns in the secondary coil, \( N_s = 100 \)
- Voltage supplied to the primary coil, \( V_p = 220 \, V \) (Note: DC voltage is supplied, but transformers operate on AC voltage. However, we will proceed with the calculation as per the provided information.)

2. **Set up the transformer equation:**
\[ \frac{V_s}{V_p} = \frac{N_s}{N_p} \]

3. **Substitute the known values into the equation:**
\[ \frac{V_s}{220} = \frac{100}{20} \]

4. **Simplify the ratio of turns:**
\[ \frac{100}{20} = 5 \]
So, we have:
\[ \frac{V_s}{220} = 5 \]

5. **Solve for \( V_s \):**
Multiply both sides by 220:
\[ V_s = 5 \times 220 \]
\[ V_s = 1100 \, V \]

### Final Answer:
The voltage across the secondary coil will be \( 1100 \, V \).