Physics 1B Flashcards
What waves are in the Electromagnetic Spectrum?
Radio waves- longest wave Microwaves Infrared Visible Light Ultra Violet X-rays Gamma rays-shortest wave
What wave is used mostly for communication?
Radio waves
What wave is used for satellite communication and mobile phones?
Microwaves
Which waves can be reflected, refracted and diffracted?
All of them
What is amplitude?
The displacement (distance) between the rest position of a wave and the crest of a wave.
What is the wavelength?
The length of a full cycle of a wave (crest to crest)
What is the frequency?
The number of complete waves passing a certain point per second. Measured in hertz (Hz)- 1 Hz is 1 wave per second.
What is the difference between a transverse wave and a longitudinal wave?
- In transverse waves, the vibrations are perpendicular to the direction of energy transfer of the wave.
- In longitudinal waves, the vibrations are parallel to the direction of energy transfer of the wave.
How do you work out wave speed?
Wave speed= frequency x wavelength
(m/s) (Hz) (m)
What waves are transverse?
- Light and all other EM waves
- Ripples on water
- Waves on strings
- A slinky spring wiggled up and down
What waves are longitudinal?
- Sound waves and ultrasound
- Shock waves (seismic waves)
- A slinky spring when you push the end
Which wave can compressions and rarefactions occur?
Longitudinal waves
What is diffraction?
Waves ‘bend around’ obstacles, causing the waves to spread out.
What is refraction?
When a wave changes speed which can cause a change of direction
Why does the amount of diffraction depend on the size of the gap relative to the wavelength?
The narrower the gap or the longer the wavelength, the more the wave spreads out.
- If the gap was the same length as the wavelength then maximum diffraction will occur
- If the gap was wider than the wavelength then there will be little diffraction
What happens during the process of refraction?
When a wave hits a boundary between two substances, for example glass to air, then the change of speed causes it to change direction.
- If the wave is travelling along the normal (the angle of incidence is 0) it will change speed but not direction- it will not get refracted.
What is the calculation to work out power?
Power= Energy transferred/ Time taken
(W)
What are the non-renewable sources of energy?
Coal
Oil
Natural Gas
Nuclear fuels
What are the renewable sources of energy?
Wind Waves/Tides Hydroelectric Solar Geothermal Food Biofuels
What are the advantages and disadvantages of wind turbines?
\+ No pollution \+ No permanent damage to the environment - No power when the wind stops - Initial costs are quite expensive - Noisy - Spoil the view
What are the advantages and disadvantages of power stations?
- Burns coal-non renewable source of energy
2. Burning of coal would release CO2 into the atmosphere- cause of climate change.
What is hydroelectric power?
- It usually involves flooding a valley by building a dam that collects falling water
- The rainwater is allowed through turbines which means there is no pollution as such.
What are the advantages and disadvantages of hydroelectric power?
+ Provides an immediate response to an increased demand for electricity
+ Useful way to generate electricity on a small scale in remote areas
- Big impact on the environment because of the flooding of a valley- rotting vegetation releases methane and CO2)
- Possible loss of habitat for some species
-/+ Initial costs are high but there’s no fuel involved and minimal running costs
