Level 2 1. Which is not true about electromagnetic waves? a. They can be seen with the bare human eye. b. They are all emitted from the Sun. c. They can be hamessed for power via solar panels. d. None of the above. 2. Which of the following regions has frequencies just slightly less than the visible region in the electromagnetic frequency. a. Infrared b. Gamma c. Microwave d. Radio waves 3. If an astronomical light source were moving toward us, what would be observed? a. Red shift b. Purple shift c. Blue shift d. Green shift 4. A sound with an intensity of 30 dB is how many times louder than the threshold of hearing? a. 10 b. 100 c. 1000 d. 10000

Let's analyze each question step by step: ### Question 1: Which is not true about electromagnetic waves? - **a. They can be seen with the bare human eye.** This statement is partially true. Only a small portion of electromagnetic waves (visible light) can be seen by the human eye. - **b. They are all emitted from the Sun.** This statement is false. While the Sun emits a wide range of electromagnetic waves, not all electromagnetic waves are emitted from the Sun (e.g., radio waves from other sources). - **c. They can be harnessed for power via solar panels.** This statement is true. Solar panels convert sunlight (electromagnetic waves) into electricity. - **d. None of the above.** This implies that all previous statements are true, which is not the case. **Conclusion:** The answer is **b. They are all emitted from the Sun.** ### Question 2: Which of the following regions has frequencies just slightly less than the visible region in the electromagnetic frequency? - **a. Infrared** Infrared has frequencies just below the visible spectrum. - **b. Gamma** Gamma rays have much higher frequencies than visible light. - **c. Microwave** Microwaves have lower frequencies than infrared. - **d. Radio waves** Radio waves have much lower frequencies than visible light. **Conclusion:** The answer is **a. Infrared.** ### Question 3: If an astronomical light source were moving toward us, what would be observed? - **a. Red shift** Red shift occurs when an object is moving away from the observer. - **b. Purple shift** This term is not commonly used in astronomy. - **c. Blue shift** Blue shift occurs when an object is moving toward the observer, indicating that the wavelengths are compressed. - **d. Green shift** This term is also not commonly used in astronomy. **Conclusion:** The answer is **c. Blue shift.** ### Question 4: A sound with an intensity of 30 dB is how many times louder than the threshold of hearing? The threshold of hearing is defined as 0 dB. The decibel scale is logarithmic, where an increase of 10 dB represents a tenfold increase in intensity. To find how many times louder 30 dB is compared to 0 dB: - 30 dB = 10 * log10(I/I0) - To find I/I0, we can rearrange this to: - I/I0 = 10^(30/10) = 10^3 = 1000 **Conclusion:** The answer is **c. 1000.** ### Summary of Answers: 1. b. They are all emitted from the Sun. 2. a. Infrared. 3. c. Blue shift. 4. c. 1000.