1.7 Radiowaves Flashcards
What causes charges to oscillate in electrical circuits?
Alternating current
How is a radio wave produced?
When a current with a frequency corresponding to the radio wave part of the spectrum is used.
How are radio waves detected?
When the waves cause an oscillating current in the conductor.
Describe in depth how we are able to generate/detect
- The oscilloscope allows us to see the frequency of the alternating current that we are using, as we can see the frequency of the wave on the screen. The frequency of the alternating current is important as it determines the frequency of the wave.
- Once the radio wave has been generated, we can detect it again by using a receiver which absorbs the energy and generates another alternating current, which is displayed using another oscilloscope.
What do radio waves allow us to do with a transmitter and a receiver?
If you’ve got a transmitter and a receiver, you can encode information in an a.c. and then transmit it as a radio wave. The wave induces an a.c. in the receiver (e.g. the aerial) and you’ve got your information.
What are the 3 different types of radio waves for communication?
- Long waves
- Short waves
- Very short waves
How can long radio waves travel across the globe?
They diffract (bend) around the curved surface of the Earth.
Describe 2 ways in which short radio waves are used in communication
- They travel long distances - they are reflected from the ionosphere (which is an electrically charged layer of the upper atmosphere) so by bouncing back and forth repeatedly, they can cover long distances.
- They can also be used for short distances, like bluetooth in your phone
Describe how very short radio waves are used in communication
They are used for T.V and FM radio. They have to travel directly from the transmitter to the receiver.
Why may you not get a good radio signal in the car?
Hills and structures may get in the way of the direct transmission.
