A step up transformer has turn ratio 10:1 . A cell of e.m.f 2 volts is fed to the primary . Secondary voltage developed is :

Options

A. 20 V
B. 10 V
C. 2V
D. Zero

Answer

To solve the problem, we need to understand the working of a step-up transformer and how the turn ratio affects the voltage.

### Step-by-Step Solution:

1. **Understand the Transformer Basics**:
A transformer operates on the principle of electromagnetic induction. It consists of two coils: the primary coil (input) and the secondary coil (output). The voltage in the secondary coil depends on the turn ratio of the coils.

2. **Identify the Given Information**:
- Turn ratio (Ns/Np) = 10:1
- EMF of the cell (V_p) = 2 volts (this is the voltage applied to the primary coil).

3. **Use the Transformer Voltage Formula**:
The relationship between the primary voltage (V_p) and the secondary voltage (V_s) in a transformer is given by the formula:
\[ \frac{V_s}{V_p} = \frac{N_s}{N_p} \]
Where:
- \( V_s \) = Secondary voltage
- \( V_p \) = Primary voltage
- \( N_s \) = Number of turns in the secondary coil
- \( N_p \) = Number of turns in the primary coil

4. **Substitute the Known Values**:
From the turn ratio, we have:
\[ \frac{N_s}{N_p} = 10 \]
Therefore, we can express the secondary voltage as:
\[ V_s = V_p \times \frac{N_s}{N_p} \]
Substituting the known values:
\[ V_s = 2 \, \text{volts} \times 10 = 20 \, \text{volts} \]

5. **Conclusion**:
The secondary voltage developed is **20 volts**.