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
