Physics test 3 Flashcards
What type of wave is a light wave?
Electromagnetic wave
What are electromagnetic waves with frequencies that are a bit higher than visible light called?
ultraviolet (UV)
Are electromagnetic waves longitudinal or transverse?
Transverse
What are 2 things all electromagnetic waves have in common?
They are Transverse and travel at the same speed (3 x 10*8) in a vaccum.
What are electromagnetic waves with frequencies that are a bit lower than visible light called?
Infrared (IR)
Who was the first person to investigate infrared radiation?
British astronomer William Hesrschel
During which years did he study Infrared radiation?
1738-1822
How did he investigate infrared radiation?
he put a dark coloured filters on his telescope to help him observe the sun safely. He noticed that different coloured filters heated up his telescope to different extents and he wondered whether the different colours of light contained different ‘amounts of heat’
What did he do to test this idea?
To test his idea he used a prism to split sunlight into a spectrum and the put a thermometer in each of the colours in turn. he also measured the temperature just beyond the red end of the spectrum ,where there was no visible light.
Give me three examples of electromagnetic waves have higher frequencies than visible light.
Ultraviolet
X - rays
Gamma rays
Give me three examples of electromagnetic waves have lower frequencies than visible light.
Infrared
Radio waves
Micro waves
What are some uses of infrared radiation?
Infrared radiation can be used for short term communication such as communication between two computers in the same room or a tv to its remote. also the information sent along optical fibers is also sent using infrared radiation
In simple terms how do thermal images work?
thermal images show the amount of infrared radiation given of by different objects
What are some uses of Microwaves?
Micro waves are used for communications and satellite transmissions
including mobile phone signals
How are radio waves produced?
radio waves are produced by oscillations in electrical circuits
What are some uses of Radio waves?
Radio waves are used for transmitting radio broadcasts and TV programmes as well as other communications. Some radio communications are sent via satellite
How are radio waves recieved?
A metal rod or wire can be used as an arial to receive radio waves
What is refraction?
the bending of the pathway due to change in velocity
How does ultraviolet disinfect water?
The energy transferred can kill microorganisms in the water
Some materials absorb ultraviolet radiation and re-emit it as visible light. what is this called?
Fluorescence
What are X-rays used for?
They can be used in medicine to make images of inside the body. They can also be for examining luggage for metal objects in airports
What are Gamma rays used for?
They can be used to sterilize food and surgical instruments , they can also be used for detecting cancer
How do you use Gamma rays detect cancer cells?
First we inject a chemical into the blood which collects inside cancer cells. This chemical emits gamma rays, then a scanner outside the body then locates the cancer by finding the source of the gamma rays
How do microwaves heat up food?
microwaves can heat water and this specific microwave frequency is used in microwave ovens.
Why could microwaves be dangerous to humans?
This heating could be dangerous to people because our bodies are mostly water so microwaves could heat up cells from the inside
Why are high frequency waves more dangerous than low frequency waves?
they transfer more energy so they are potentially more dangerous.
What are some risks of long exposure to x rays or gamma rays?
mutations may appear in DNA that can kill cells or cause cancer
