Waves And EM Spectrum

Question 1

Refraction between air and glass

Answer 1

When wave hits a boundary it changes speed
When air—>glass slows down
One part of wavefront reaches glass and slows
By the time the rest of the wavefront reaches the boundary it would have travelled further and so the wave bends

Question 2

How does wavelength affect how much a wave refracts

Answer 2

Larger wavelength waves bend less
Smaller wavelength (higher frequency) wave bends more

Question 3

Frequency

Unit?

Answer 3

Number of complete wave cycles per second

1 Hz = 1 wave per second

Question 4

How are radio waves are made

Answer 4

Alternating current in an electrical circuit produce oscillating electric and magnetic fields
EM waves are made up of oscillating electric and magnetic fields
The radio waves are created in the transmitter and emitted to the receiver

Question 5

Radio waves and their use for communication and broadcasting

Answer 5

• Long wave radio waves curve along the Earth’s surface and so can travel around the world
• short wave radio waves are reflected by the Earth’s watery atmosphere- can send over very long distances

Question 6

Microwaves and radio waves used by satellites

Answer 6

Microwaves and very high frequency radio waves can pass through the Earth’s watery atmosphere to a satellite (transmitter)
Transmits signal back to Earth to a satellite dish

Question 7

How to measure speed of sound

Answer 7

Attach a signal generator to a speaker
Use two microphones and connect to an oscilloscope
Put both microphones next to the speaker and move one away until the waves are aligned on the oscilloscope
Distance between microphones= 1 wavelength
Frequency is what you set the signal generator to
Speed of sound = wavelength x frequency

Question 8

How to measure speed of water ripples

Answer 8

-Using a signal generator create water waves at set frequency
-Turn on strobe light and alter frequency so waves appear to freeze- frequency of wave and strobe light are equal
-Wavelength = Distance between each shadow
-Frequency = what the signal generator is set at
Wave speed= wavelength x frequency

Question 9

How to find speed of waves in solids using peak frequency

Answer 9

-When hit, the rod produces sound waves at the same frequency as the waves vibrating in the rod
-measure length of rod
-record the highest frequency of the sound waves- displayed by computer
Speed = frequency x wavelength