What will increase in step-down transformer?

Options

A. Voltage
B. Current
C. Power
D. Current density

Explanation

To solve the question "What will increase in a step-down transformer?", we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Transformer Basics**:
A transformer is a device that transfers electrical energy between two or more circuits through electromagnetic induction. It operates on alternating current (AC) and consists of primary and secondary coils.

**Hint**: Remember that transformers work on the principle of electromagnetic induction.

2. **Types of Transformers**:
There are two main types of transformers:
- **Step-up Transformer**: Increases voltage from primary to secondary.
- **Step-down Transformer**: Decreases voltage from primary to secondary.

**Hint**: Identify the difference between step-up and step-down transformers based on their function regarding voltage.

3. **Power Conservation in Transformers**:
The power in a transformer is given by the formula:
\[ P = E \times I \]
where \( P \) is power, \( E \) is voltage, and \( I \) is current. In an ideal transformer, the power input equals the power output, meaning:
\[ P_{primary} = P_{secondary} \]

**Hint**: Recall that power remains constant in an ideal transformer.

4. **Behavior of a Step-down Transformer**:
In a step-down transformer, the number of turns in the secondary coil is less than that in the primary coil. This results in a decrease in the output voltage (secondary voltage).

**Hint**: Focus on how the number of turns affects voltage and current in the transformer.

5. **Effect on Current**:
Since the power must remain constant, if the voltage decreases in a step-down transformer, the current must increase to compensate for this decrease in voltage. Therefore, we can conclude that:
\[ I_{secondary} = \frac{P_{primary}}{E_{secondary}} \]
As \( E_{secondary} \) decreases, \( I_{secondary} \) must increase to keep \( P \) constant.

**Hint**: Use the relationship between voltage and current to understand how they affect each other in a transformer.

6. **Final Conclusion**:
In a step-down transformer, while the voltage decreases, the secondary current increases.

**Hint**: Summarize the relationship: in a step-down transformer, as voltage decreases, current increases.

### Final Answer:
In a step-down transformer, the secondary current increases.