What do waves do?
Transfer energy and information without transferring matter
What is frequency?
The number of waves passing a point each second, measured in Hertz
What is period?
The time taken for one wavelength to pass a point. 1/frequency
What are the similarities between longitudinal and traverse waves?
They both transfer energy without transferring matter, both have an amplitude, speed, wavelength and frequency
What are the differences between longitudinal and traverse waves?
Particles in longitudinal waves vibrate along the direction of movement whereas particles in traverse waves move at 90 degrees to the direction of travel
Wave speed equation?
Frequency x wavelength
Wave speed x time
What are the properties of electromagnetic waves?
All are transverse, all travel at 3 x 10^8 in a vacuum, all transfer energy to the observer
What is the order of the electromagnetic spectrum?
Radio waves, microwaves, infrared, visible light, ultraviolet, x-ray, gamma rays
What has the longest wavelength?
What has the highest frequency?
What are the uses of radio waves?
Broadcasting radio and TV, communicating with ships, aeroplanes and satellites
What are the uses of microwaves?
In mobile phones to communicate by satellite transmission, for cooking
What are the dangers of microwaves?
They heat water, so they can heat the water in your body
What are the uses of infrared?
Cooking, thermal images, TV controls where the signal only travels short distances
What are the dangers of infrared?
It transfers thermal energy and too much can cause skin burn
What are the uses of visible light?
Allows us to see, illumination, photography
What are the uses of ultraviolet?
To detect security marks, to detect forged bank notes, to disinfect water
What are the dangers of ultraviolet?
UV in sunlight can damage skin cells causing sunburn, overtime exposure can cause skin cancer, it can damage cells
What are the uses of x-rays?
To look inside objects
What are the uses of gamma rays?
To sterilise food and medical equipment, in scanners to detect cancer, to help treat cancer
What are the dangers of gamma and x-rays?
They can cause mutation to the DNA cells in the body, this may kill cells or cause cancer