P1.5 Flashcards
What does red shift show?
That a star is moving away from Earth
What does blue shift show?
That a star is moving towards Earth
Why does a star moving away look red?
Because the waves it produces behind it are stretched out and have a long wavelength, which makes them appear red
What does a star moving towards earth look blue?
Because the waves it produces infront of it are compressed and have a short wavelength, which makes them appear blue
What does red galaxies in the sky prove?
That at some point in the past the galaxies must’ve been together, and the entire universe is expanding
What is cosmic microwave background radiation?
A type of radiation which is believed to have been present shortly after the Big Bang
What is the Big Bang theory?
It states that the universe started from a precise small point billions of years ago and has been expanding since
What led to the scientific community accepting the Big Bang theory?
The discovery of CMBR in the 1960s
When we look at the sun why are some frequencies of light not seen?
Because they’re absorbed by hydrogen and helium
A more distant galaxy is doing what?
Moving away faster
What is amplitude?
The peak of movement of the sound wave from its rest point
What does the amplitude affect?
The loudness of the sound
What type of waves does sound travel as?
Longitudinal waves
How are sound waves produced?
By something vibrating
What are some properties of sound waves?
~ Can’t travel through a vacuum
~ Reflect off hard surfaces to produce echoes
~ Refracted when it passes into a different medium or substance
~ Diffracted around buildings or land masses
What is the frequency of a sound wave?
The number of vibrations produced in one second
How does frequency affect sound?
It affects the pitch
What is frequency measured in?
Hertz (Hz)
What is a use of the different waves in the electromagnetic spectrum?
Radio waves - TV signals
Microwaves - Bluetooth devices / satellite communication
Infrared rays - Remote controls
Visible light - Photography
Ultraviolet rays - Sunbeds
X-Rays - Producing shadow pictures of bones
Gamma rays - Killing cancerous cells
What are risks associated with ultraviolet rats, X-Rays and gamma rays?
High doses can kill (cancerous) cells and low doses can cause cancer
What are risks associated with radio waves?
High exposure can increase body temperature, leading to tissue damage, especially to the eyes
What are risks associated with microwaves?
They’re absorbed by water in the cells causing a release of heat and damaging or killing cells
What are risks associated with infrared rays?
Absorbed by skin, can cause burns
What is the wave speed?
How quickly the energy moves, m/s
What’s an example of a transverse wave?
Waves in water
What are the oscillations like in a transverse wave?
The oscillations in a transverse wave are perpendicular to the direction of energy transfer
What are the oscillations like in a longitudinal wave?
The oscillations in a longitudinal wave are parallel to the direction of energy transfer
What are the points on a longitudinal wave called when the lines are bunched together?
Compressions
What are the points on a longitudinal wave called when the lines are spread out?
Rarefactions
What is an image produced by a mirror like?
~ Virtual
~ Upright
~ Laterally inverted
When is diffraction greatest?
When the gap is the same width as the wavelength
What type of waves are electromagnetic waves?
Transverse waves
What are properties of electromagnetic waves?
~ Can travel through a vacuum
~ Travel at the same speed though a vacuum
~ Can be reflected and refracted
What wave has the highest frequency and the shortest wavelength?
Gamma rays
What wave has the lowest frequency and the longest wavelength?
Radio waves
How is the visible light spectrum produced?
White light is made of different colours which are refracted by different amounts as they pass through a prism - red light is refracted the least and violet is refracted the most
