1. What is the highest frequency humans can hear?

• A). 10 kHz
• B). 20 kHz
• C). 100 kHz
• D). 200 kHz

2. What is the lowest frequency humans can hear?

• A). 10 Hz
• B). 20 Hz
• C). 100 Hz
• D). 200 Hz

3. The diagram here shows the human ear.

3. What are the missing parts labelled X and Y?

4. Dolphins and submarines use very high frequency sound waves to find the location of objects under the oceans. This technique is called...

• A). radar
• B). pulse scanning
• C). microwave location
• D). sonar

5. When sound waves move from water into air, they slow down. Which statement below explains the changes, if any, to the frequency and wavelength of sound waves in this situation?

• A). Wavelength increases, frequency decreases.
• B). Wavelength increases, frequency stays the same.
• C). Wavelength stays the same, frequency decreases.
• D). Wavelength decreases, frequency stays the same.

If the pulse echo is detected 4 seconds later, how deep is the ocean at this point?

• A). 3 km
• B). 4 km
• C). 5 km
• D). 6 km

8.Reflection in a single direction, as shown in question 7, is called....

• A). diffuse reflection.
• B). external reflection.
• C). specular reflection.
• D). linear reflection.