Radiation and the Universe
Physics P1b
- Created by: Kitty Bazalgette
- Created on: 11-02-11 17:10
Question
What are waves?
Answer
Waves are vibrations that transfer energy from place to place without matter (solid, liquid or gas) being transferred.
Question
What do some waves travel through?
Answer
Solid, liquid or gas
Question
What is a seismic wave?
Answer
Vibrations caused by the earth
Question
What do other waves travel through?
Answer
Empty space
Question
What is amplitude?
Answer
The volume of a wave
Question
What is frequency and what is it measured in?
Answer
The amount of waves per second.
Hertz (Hz)
Question
How fast do waves travel?
Answer
wave speed (metre per second) = frequency (Hz) x wavelength (metres)
Question
What is the visible spectrum?
Answer
When light is refracted the shorter the wavelength of the light, the more it is refracted. As a result, red light is refracted the least and violet light is refracted the most, causing the coloured light to spread out to form a spectrum
Question
What is the electromagnetic spectrum?
Answer
Visible light is just one type of electromagnetic radiation. There are various types of electromagnetic radiation, some with longer wavelengths than visible light and some with shorter wavelengths than visible light.
Question
What are the different types of waves?
Answer
Gamma highest
X-ray
Ultraviolet
Visible light
Infra Red
Micro-waves
Radio-waves lowest
Question
What are their uses?
Gamma - killing cancer cells
X-ray - medical images of bones
Ultraviolet - detecting forged bank notes by fluoresence
Visible light - seeing
Infra Red - optical fibre communication
Micro-waves - cooking
Radio-wave - television signals
Question
What are scientists main theory on the how the universe began?
Answer
Scienctists main theory is the Big Bang. The theory states that originally all the matter in the universe was concentrated into a single incredibly tiny point. This began to enlarge rapidly in a hot explosion, and it is still expanding today.
Question
How long ago was the big bang?
Answer
13.6 billion years ago
Question
What is the Doppler effect?
Answer
where there is a change in frequency and wavelength
Question
What do atoms contain?
Answer
Three sub atomic particles
protons, neutrons and electrons
Question
Where are the protons electrons and neutrons found?
Answer
The protons and neutrons are found in the nucleus of the atom and the electrons are arranged in energy levels or shells around the nucleus
Question
What are isotopes?
Answer
Atoms that have different numbers of neutrons in the nucleus
Question
What is an Alpha particle?
Answer
- it is a helium nucleus
- it is made up of 2 protons and 2 electrons
Question
What is a beta particle?
Answer
- a high speed electron from the nucleus
- it is emitted when a neutron changes to an electron and proton (the proton remains in the nucleus)
Question
What is gamma radiation?
Answer
- a very short wavelength electromagnetic radiation that is emitted from the nucleus
Question
How penetrating are these radioactive substances
- Alpha
- Beta
- Gamma
Answer
- Alpha - not penetrating. can be stopped by a thin piece of paper, human skin or even a few centimeters of air
- Beta - they penetrate further than alpha and will be blocked by a few meters of air or a thin sheet of aluminum
- Gamma - very penetrating. several centimeters of lead and several meters of concrete are needed to block it.
Question
What is half life?
Answer
The time it takes
- for the number (and also mass) of parent atoms in a sample to halve
- for the count rate from the original substance to fall to half its initial level
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