*Question E7D10:
Why is a switching type power supply less expensive and lighter than an equivalent linear power supply?*  

*Correct Answer is  C: The high frequency inverter design uses much smaller transformers and filter components for an equivalent power output*  

### AI Response: (may contain errors)  

Switching type power supplies are often preferred over linear power supplies for several reasons, primarily related to size, weight, and cost efficiency. Let's break down why the correct answer is correct and why the other choices are incorrect.

### Correct Answer: C
**The high frequency inverter design uses much smaller transformers and filter components for an equivalent power output**

1. **High Frequency Operation**: Switching power supplies operate at high frequencies, often in the range of tens to hundreds of kilohertz (kHz). This high frequency allows the use of much smaller transformers and inductors compared to linear power supplies, which operate at the standard AC line frequency (50 or 60 Hz).
2. **Size and Weight**: Smaller transformers and inductors mean the power supply can be lighter and more compact.
3. **Cost Efficiency**: Smaller components generally cost less, contributing to the overall lower cost of the power supply.

### Why Other Choices Are Incorrect:

- **Choice A**: "The inverter design does not require an output filter circuit"
  - **Incorrect**: Switching power supplies do require output filter circuits to smooth out the high-frequency switching noise and provide a stable DC output. The filter components are smaller due to the high frequency, but they are still necessary.

- **Choice B**: "The control circuitry uses less current, therefore smaller heat sinks are required"
  - **Incorrect**: While switching power supplies are more efficient and generate less heat than linear supplies, the primary reason for their reduced size and cost is the smaller magnetic components, not just the reduced need for heat sinks.

- **Choice D**: "It recovers power from the unused portion of the AC cycle, thus using fewer components"
  - **Incorrect**: This statement is misleading. Switching power supplies do not recover power from the AC cycle in this manner. Their efficiency comes from the high-frequency operation and the ability to efficiently convert power with minimal losses, not from recovering unused power.

### Summary
Switching power supplies are more efficient and compact due to their high-frequency operation, which allows for smaller transformers and filter components. This is the primary reason they are less expensive and lighter than equivalent linear power supplies.