Unit 3 - Lesson 8: Sound Waves Flashcards
(26 cards)
What is sound produced by?
Sound is produced by a vibrating object.
The more times an object vibrates per second, the more what is produced per second?
The more times an object vibrates per second, the more waves produced per second. Therefore, the higher frequency.
What do the vibrations of an object vibrate in the surrounding air?
The vibrations of the object vibrate particles in the surrounding air.
Why can’t sound travel in space?
There are no air particles to vibrate.
What do animals like bats and whales use to locate food?
What is echo sounding?
Sonar. They produce sound waves and detect how they are reflected to indicate objects nearby.
Humans use the same principle on boats to detect how deep the water is. This is called echo sounding.
Why can sounds appear louder over a lake?
This is because of sound refracting.
How do sound waves travel?
Sound waves travel via the movement of particles.
Does sound travel faster in hotter air? Why or why not?
Yes, because as temperature increases, particles move more (have more kinetic energy). Therefore, sound travels faster in hotter air.
What kind of temperature is the air directly above a lake? How does this temperature effect sound travelling?
It’s generally cooler than air higher up. This means sound travels slower closer to the water’s surface and faster higher up.
If someone shouts across a lake, the listener essentially receives two sets of sound (it’s amplified).
How is sound likely to react to entering water from air?
It will increase in speed.
It will be refracted.
State the correct order of EM radiation from longest to shortest wavelength.
radio, microwave, infrared, visible light, ultraviolet, x-ray, gamma
Are sound waves longitudinal or transverse?
Longitudinal
Define the period of a wave.
The time it takes for one complete wave to pass a point.
Whales and dolphins talk to each other by echolocation, which involves transmitting sound waves through water. Would you be able to hear the whale from a boat without special equipment? Why or why not?
Unlikely, as sound travels slower through air than water.
Why is the refractive index (n) unitless?
It’s a ratio.
As refractive index of a material gets higher, does the speed of light moving through it get slower or faster?
Slower.
The denser the material, the (higher/lower) the refractive index.
The denser the material, the HIGHER the refractive index.
The denser the material, the (higher/lower) the refractive index. The refractive index of air is close to 1.003. What do you think is the refractive index of a vacuum?
1.0
Which process do binoculars use?
Reflection
Give one example of good care that should be taken with fibre optic cables.
The fibre optic cable should not be bent.
What can pierce the ionosphere?
Very short wave radio
What is the result of compression and rarefactions in a sound wave?
Small differences in air pressure
An image of a tiger was taken using a night vision camera that uses infrared. Explain how the camera detected the animal.
The tiger gives off heat i.e. infrared radiation. The camera detects infrared.
What is the speed of any EM radiation in free space?
The speed of light
