*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)  

The correct answer to the question about why a switching type power supply is less expensive and lighter than an equivalent linear power supply is:

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

### Explanation of the Correct Answer:
- **High Frequency Operation**: Switching power supplies operate at high frequencies (typically tens to hundreds of kHz), which allows the use of smaller transformers and inductors. The size of these components is inversely related to the frequency; as frequency increases, the size of the magnetic components can decrease significantly.
- **Efficiency**: Because they can operate efficiently at these higher frequencies, switching supplies can convert power with less heat generation, which also contributes to their lighter weight and lower cost.

### Why the Other Choices are Incorrect:
- **A: The inverter design does not require an output filter circuit**  
  - This is incorrect because switching power supplies do require output filtering to smooth the output voltage. While they may use different filtering techniques, they still need components to reduce ripple.

- **B: The control circuitry uses less current, therefore smaller heat sinks are required**  
  - While it is true that switching supplies can be more efficient and generate less heat, the primary reason for their reduced size and cost is not solely due to the control circuitry using less current. The heat sinks are still necessary, but they are smaller due to the overall efficiency of the design.

- **D: It recovers power from the unused portion of the AC cycle, thus using fewer components**  
  - This statement is misleading. Switching power supplies do not recover power from the unused portion of the AC cycle. Instead, they convert AC to DC and then switch it on and off rapidly to control the output voltage. The design does not inherently reduce the number of components based on recovering unused power.

### Summary:
Switching power supplies are lighter and less expensive primarily due to their high-frequency operation, which allows for smaller transformers and filter components. Understanding the differences between switching and linear power supplies is crucial for the Extra Class exam, as it highlights the advantages of modern power supply designs.