Chapter 12 - Using Waves Flashcards
How do waves at one end of the EM spectrum differ from waves at the other end? (2 marks)
- One end is high frequency, short wavelength - Other end is low frequency, long wavelength
What 4 properties do all waves have? (4 marks)
- All transfer energy - All transverse waves - Travel at the speed of light in a vacuum - All can be reflected, refracted and diffracted
Radio waves have the ……. wavelength in the EM spectrum (1 mark)
Longest, meaning low frequency
How are radio waves used in TV and FM radio (3 marks)
- Given out by a transmitter - As they cross an aerial, they are detected and info they carry can be received - TV and FM radio use radio waves with short wavelengths to carry their signals
What are the sources and detectors for radio waves (2 marks)
Sources - Radio and TV transmitters Detectors - Radio and TV aerials
Microwaves have a …. wavelength and a … frequency (2 marks)
- Long - Low
How do microwaves heat food (5 marks)
- Special electrical circuits produce microwaves - Metal guides direct microwaves towards a rotating reflector - This reflector sends microwaves in all directions - Microwaves are reflected from metal casing - Food absorbs microwaves and becomes hot
Two uses of microwaves (4 marks)
- Cooking : microwaves are used as food absorbs microwaves and becomes hot - Phones : messages sent to and from mobile phones are also carried by microwaves
What are the sources and detectors for microwaves (2 marks)
Sources - microwave transmitters and ovens Detectors - microwave receivers
Describe two differences between X-rays and visible light (2 marks)
- X-rays have shorter wavelength - X-rays have higher frequency
State the name of the type of wave that includes X-rays and visible light
electromagnetic
Which of the following is NOT a medical use of X-rays? A - Pre-natal scanning B - CT scans C - Killing Cancer Cells
A - Pre-natal scanning
True or false? X-rays can be used to diagnose dental problems.
True
Are X-rays absorbed or transmitted by metal?
absorbed
True or false? X-rays can be used to break up kidney stones.
False
EM SPECTRUM ACRONYM
Raging
Martians
Invaded
Venus
Using
X-ray
Guns
A microwave cooker is often said to ‘cook the food from the inside’
Explain whether this statement is true by describing how energy is transferred to heat up all of the potato [3 marks]
- Microwaves are electromagnetic waves
- They cause water molecules to vibrate more / heat water
- Conduction through the rest of the potato
- Electromagnetic induction
- Coil creates magnetic field around it
- Which cuts through the metal pan
- Inducing a voltage in the pan;
- Causing a current in the pan
- Current makes the pan get hot
- Which heats the water by conduction
- Water convects energy to potato;
Suggest a property of radio waves that makes them suitable for use in communication [1 mark]
Can travel long distances
Describe a possible harmful effect on people of microwaves [1 marks]
heating
Describe a use of ultraviolet rays [1 marks]
kill bacteria
Possible harmful effect on people of ultraviolet rays [1 marks]
skin cancer
Explain what is meant by a digital signal [2 marks]
- Signal has two values
-
Suggest two ways that this signal could be made to carry more information [2 marks]
- Increased frequency of wave
- using increased bandwidth;
