1. Waves (I)
S3 Physics - 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

2. sound waves with a frequency above 20,000Hz
1. What is meant by the term: ultrasound
answer
sound waves with a frequency above 20,000Hz

3. 2. What is the speed of light in air?
answer
300,000,000ms-1

4. 3. A car has a parking sensor that emits ultrasound waves
3. A car has a parking sensor that emits ultrasound waves. They have a frequency of 40kHz ..Calculate their wavelength
answer

5. 4. A car stops 1.7m from a wall. Calculate the time for an ultrasound pulse from a parking sensor to reflect from the wall and return to the car.
answer

6. The time will increase as it has further to travel
5. The car moves further from the wall, what happens to the time taken for the Ultrasonic wave to return to the car?
answer
The time will increase as it has further to travel

7. Radio waves have a longer wavelength than TV waves and diffract more
6. Why can we get a good radio signal in hilly areas but a poor TV signal?
answer
Radio waves have a longer wavelength than TV waves and diffract more

8. 7. What is meant by the frequency of a wave?
answer
Number of complete waves that pass a point in one second

9. 8. Are light waves transverse or longitudinal waves?
answer
Transverse

10. 9.What is the frequency range of human hearing?
answer
20Hz-20,000Hz

11. What is the threshold of pain for the human ears?
answer
130dB

12. 11. Give a use of ultrasound in medicine.
answer
Scanning an unborn baby in the womb

13. 12. True or false…Long wave are diffracted more than short waves?
answer
True

14. 13. How could we protect our hearing from becoming damaged?
answer
Wear ear muffs (ear protectors) that absorb some of the sound energy.

15. 14. Which sound has a higher pitch: a high frequency wave or a low frequency wave?
answer
High frequency

16. 15. Why can sound not travel in a vacuum?
answer
There are no air particles to carry the vibrations.

17. 16. The frequency of a wave is 200Hz, Calculate the Period of this wave.
answer .