Did You Get The Message? Flashcards
What is meant by the amplitude of a wave?
It is the distance from the centre of the wave to the crest or trough.
Describe how to measure the speed of sound with two students using a clapper board, stop watch and trundle wheel.
- One student takes the clapperboard and stands still.
- The other students takes the stop watch and uses the trundle wheel to measure a set distance away.
- The first student shuts the clapper board.
- The other student starts the stop watch when they see the clapper shut and stops it when they hear the sound.
- Speed of sound is calculated by distance between the students divided by the time on stop watch.
What is the energy change in a microphone?
Sound to electrical energy
You are 10km from a thunder storm. You count 15 seconds between seeing the lightning and hearing the thunder. You repeat this after the next lightning strike, the time between the lightning and the thunder is now 10 seconds. What does this tell you?
The storm has moved closer to you.
What is the purpose of the tuner in a radio?
To select one frequency
On an oscilloscope screen what would a loud sound look like?
Wave with a large amplitude - tall wave
What is the purpose of the amplifier in a radio?
To make the weak signal stronger
What is the unit for frequency?
Hertz (Hz)
Give an advantage of mobile phones
- No wires - can be used anywhere
- Acts as many devices
- Can always be in contact with people
- Fast to use in an emergency
What is the purpose of the aerial in a radio?
To detect all radio frequencies
Give an advantage of using a Landline phone system
- Easy to understand message
- Fast
- Sends speech rather than a code
What is the unit for wavelength?
Metres (m)
What do waves transfer?
Energy
What is the difference in the two waves shown below?
The top wave has a bigger amplitude and so has more energy.
(Or the bottom wave has a smaller amplitude so has less energy)
What is the purpose of the decoder in a radio?
Picks out the useful audio part of the signal
Describe how to measure the speed of sound using the equipment below.
- Make a loud sound to the left of the first microphone.
- When the sound reaches microphone one it starts the fast timer, when the sound reaches the second microphone this stops the timer.
- Measure the distance between the microphones using a metre stick.
- The speed is calculated from distance between the microphones divided by the time on fast timer.
What happens to the speed of light as it travels from air into glass?
The speed of light in glass is slower than the speed of light in air.
What is the unit for speed?
metres per second (ms-1)
Does a light ray always change direction when it undergoes refraction?
No.
Which device can be found in the mouthpiece of a landline phone?
Microphone
Which wave property is illustrated below?
Wavelength
On an oscilloscope screen what would a high frequency sound look like?
Many waves on the screen
What speed does light travel at in an optical fibre?
2 x 108ms-1
What is the unit for time?
Seconds (s)
Explain how to send a signal using a Morse Code telegraph.
- When the switch is closed the circuit is completed.
- Hold the switch down for a long time to get a dash, a short time for a dot
- Use an agreed code
What happens to a light ray as it travels from water into air?
It speeds up and changes direction away from the normal.