Physics CT4 Flashcards by Zara Bates

define nucleons

subatomic particles which make up the nucleus

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what is nuclear radiation

when unstable isotopes have energy that they want to lose

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what are the 3 types of nuclear radiation

-alpha
-beta
-gamma

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how are radio waves made?

by alternating currents in a metal

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how are gamma rays made?

from radioactive materials

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what is the energy level of the further out the shell of an electron orbit?

higher energy level

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What was J. Daltons theory of the model of the atom?

-every element has a different type of atom
-the atom can’t be broken up
-atomic spheres

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What was J.J.Thompsons theory of the model of the atom?

-atom is a positive dough
-electrons scattered through it
-you can pick the electrons out
-plum pudding model

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What was E.Rutherfords theory of the model of the atom?

-very small nucleus (dense)
-electrons around the outside
-positive and negative
-nuclear model

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What was N.Bohrs theory of the model of the atom?

-electrons exist in orbital shells
-equally distanced apart
-atomic model

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What happens if an atom absorbs some energy?

it can excite an electron to a higher energy level (orbit)

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What is the lowest level of energy called?

ground level

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What do electrons require to move different levels?

as they are picky they require specific amounts of energy to move

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What are the different radiations on the EM spectrum in order largest to smallest?

-radio
-microwave
-infrared
-visible
-ultraviolet
-xrays
-gamma

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what radiations of the EM spectrum is ionising

-ultraviolet
-xrays
-gamma

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how does the energy differ between the colours?

different colours of light has different amounts of energy.
-red has lower energy than violet

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define ionisation

when an atom becomes an ion if it has a net charge, (more protons than electrons or vice versa)

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What happens if a nuclei has too much energy and are unstable?

they can release the energy undergoing radioactive decay and release a particle or a gamma ray

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what is an alpha particle

-made of 2 protons and 2 neutrons
-helium nucleus

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what is the ionising info about an alpha particle

-ionise as they interact
-highly ionising
-paper is enough to stop it
-few cm in air

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What is a beta particle

-an electron made when a neutron turns into a proton and electron

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what is the ionising info about a beta particle

-around 5mm of aluminium
-50cm in air

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what is a gamma particle

electromagnetic wave
(light)

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what is the ionising info about a gamma particle

-weak ionisation
-large distance
-thick lead or concrete

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Why does Beta minus do radioactive decay?

-too many neutrons

what is the equation for beta minus in radioactive decay

neutron --- proton + electron -the electron is the beta minus

why does beta plus do radioactive decay

-too few neutrons

what is the equation for beta plus in radioactive decay

proton --- neutron + antielectron/positron -the positron is the beta plus

what does the term 'half life' mean?

the time it takes for half of the unstable nuclei to decay -it is a random process

define food irradiation

some radiation sources can be used to sterilise food

define irradiation?

a person is irradiated if they are exposed to radiation from a radioactive source

define contamination?

-a person is contaminated if bits of radioactive material gets into their skin or inside them -if someone is contaminated, they will continue to be irradiated until the radioactive material has all decayed or the source has been removed

what can large amounts of ionising radiation cause?

skin burns

what can small amounts of ionising radiation cause>

over a long period of time can cause damage to DNA inside the cells causing mutations

what are the different precautions to take to limit the risk of radiation?

-keep distance between yourself and the source -reduce time that you are being exposed to it -use shielding (gloves or any form of lead shielding)

define geocentric

the earth is the centre of the model of the solar system

who was the first person to put forth a model of the solar system

Ptolomy, an ancient greek astronomer

what was Ptolomys idea of the solar system

planets moved in circles as they orbited the earth

what did Nicolaus Copernicus believe?

that Pyolomy's measurements fitted the heliocentric model

define heliocentric

the sun was at the centre around the system with everything orbiting that instead

what was Galileaos theory of the solar system?

-supported copernicus idea. -he discovered the telescope and 4 of jupiters moons by monitoring their movements which showed that not everything orbited the earth

define satellites

a body that orbits the Earth, or another cosmic body

examples of natural satellites

moons

examples of artificial satellites

GPS satellites, Sky TV satellites, the International Space Station

define comet

big ball of ice (mostly water and frozen gases), it has a very elliptical orbit

what shape do planets orbit?

ellipse orbit so not perfect circles

define asteroid

rocks, mostly found between Mars and Jupiter

what is pluto

-dwarf planet as it is very small and has a very elliptical orbit and doesn't lie on the same plane as Earth. -the planet crosses Neptune's orbit and doesn't have a distinct orbit around the sun

what is a refracting telescope

-bends light on the many lenses inside to make the image bigger (magnify it). -only make the image so big and means only collect so much light

what is a reflecting telescope

-has a mirror that captures light and focuses it to the image -it doesn't sag and can collect more light and therefore make the image bigger -you can see more things clearer that are further away

define array

collection of small objects together (lots of small telescopes)

define energy

-measured in Joules -defined as the capacity to do work

define work done

-energy can be transferred when a force moves something. the energy transferred is the work done

how to calculate the work

force times distance

define power

the rate at which energy is transferred

how to calculate power

energy divided by time

how to calculate KJ to J

/ 1000

define a contact force

a force between two objects caused by them being in contact

define non-contact force

a force between two objects which aren't in contact

examples of non-contact forces

-gravity -magnetism -electrostatic

examples of contact forces

-friction -air-resistance -reaction force (normal)

define force field

an area in which an object will experience a force

define resultant vector

vectors can be added together into one simplified vector

define current

the amount of electrons passing each second

how to calculate electrical power

current times potential difference

define potential difference

the amount of energy transferred to each electron

Physics CT4 Flashcards

(66 cards)