*Question G3A03:
Approximately how long does it take the increased ultraviolet and X-ray radiation from a solar flare to affect radio propagation on Earth?*  

*Correct Answer is  C: 8 minutes*  

### AI Response: (may contain errors)  

When a solar flare occurs, it releases increased levels of ultraviolet (UV) and X-ray radiation. This radiation travels at the speed of light, which is approximately $299,792,458$ meters per second.

1. **Correct Answer: 8 minutes (Choice C)**
   - The distance from the Sun to Earth is about $93$ million miles, or approximately $150$ million kilometers. Light takes about $8$ minutes to travel this distance. Therefore, the increased UV and X-ray radiation from a solar flare affects radio propagation on Earth in about $8$ minutes.

2. **Why the Other Choices are Incorrect:**
   - **Choice A: 28 days**  
     This is the approximate time it takes for the Sun to complete one rotation on its axis. It is not related to the time it takes for radiation to travel from the Sun to Earth.
   - **Choice B: 1 to 2 hours**  
     This time frame is too long for radiation traveling at the speed of light. It might be confused with the time it takes for other solar phenomena, like solar wind, to reach Earth.
   - **Choice D: 20 to 40 hours**  
     This is the typical time it takes for a coronal mass ejection (CME) to reach Earth, not the time for UV and X-ray radiation.

3. **Useful Rule of Thumb:**
   - Light and electromagnetic radiation from the Sun, including UV and X-rays, take about $8$ minutes to reach Earth. This is a key concept in understanding how quickly solar flares can impact radio propagation.