P2 Phy Flashcards
What is the atomic number?
The number of protons in an atom
What is the mass number?
The total number of particles in the nucleus
Protons + neutrons
What are isotopes?
When atoms have the same number of protons but has different numbers of neutrons
What are ions?
A molecule that has either lost (positive) or gained (negative) electrons
What kind of nucleus do radioactive elements have?
An unstable nucleus
What is radioactive decay?
Unstable nucleus release and emit radiation and form a different nucleus
What is background radiation?
Low level of radiation around us
What are man made sources of radiation?
Atomic bomb tests
Nuclear power plants
Nuclear equation of Alpha radiation?
4 less protons (top)
2 less mass number (bottom)
Nuclear equation of Beta Decay?
0 less protons (Top)
1 less mass number (bottom)
What is the charge of alpha radiation?
2+
What is the charge of beta radiation?
-1
What is the charge if gamma radiation?
No charge
What are the distances between alpha, beta and gamma radiation?
Alpha particles can travel a few centimeters
Beta can travel through a few meters
Gamma can travel a long way
What does ionizing radiation mean?
Radiation ionize atoms to form charged ions
What is the danger of ionization?
They damage or kill cells
Why is alpha radiation more dangerous than gamma or beta radiation?
Alpha radiation has a short range so it will ionize everything close
Beta and gamma radiation have a long range so it will travel far before it could ionize cells
Give one positive use of alpha particles and explain how
Alpha particles can be used in smoke detectors. It neutralizes charged particles in smoke and the number of charged particles In the air will reduce. The detector will detect the change and the alarm will go off
What are the uses of beta radiation?
Beta particles can damage cancer cells without causing too much damage to healthy cells
It can use to measure thickness of paper in factories
What are the uses of gamma radiation?
They are used as medical traders
Detect cracks in pipes
What are the 3 types of particles do atoms contain?
Protons
Neutrons
Electrons
What is nuclear fission?
Fission is the splitting of nucleus in an atom
What is the chain reaction of nuclear fission?
As nuclei is split, this will continue
What does a moderator do in nuclear reactors?
What does it contain?
It slows down the neutrons give out by nuclear substances such as uranium 235
It contains graphite or water
What does the control rods do?
They control the speed of the reaction
What is nuclear fusion?
The combination of nuclei to form a larger nucleus and release energy
What are the common fuel for nuclear fusion?
Deuterium and tritium
Life cycle of a sun-like star
Huge clouds of gas and dust (nebulae)
Pulled by gravitational forces
It begins to compress and warms up
This forms a spinning disc of hot gas (protostar)
Fusion begins, a true star is formed
It blows if other layers of gas and dust
The star is halfway through, so it will start the main sequence and last another 5 billions years
Once hydrogen fuel is used, the star will swell up and become bigger (red giant) that lasts tens of thousands of years
Core collapses, a white dwarf will be formed
What is the supernova?
When the core of a star collapses even more and explodes, releasing a lot of energy
What is a neutron star?
A ball of matter formed when the core collapsed
What is the black hole?
Small ball of very dense matter
How are heavier elements were formed?
Hydrogen was formed a few billion years after the Big Bang
A few stars were formed a million years later
This formed heavier elements, that exploded, scattering pieces across space
Newer stars are formed containing heavier elements from older exploded stars
How to protect ourselves from radiation?
Keep distances between ourselves and radioactive source
What are half lives?
Average time it takes for something to decline by half
Law of force
The action force is matched by the reaction force
What is acceleration?
The measure of how quickly something gets faster
What is momentum?
Mass of an object multiplied by its velocity
What is the law conservation of momentum?
If 2 objects collide, the total momentum is the same before and after the collision
What is the use of KERS?
It’s a way of making a vehicles braking system more energy efficient
What is static electricity?
A charge in an object caused by the addition or removal of electrons
What is oh mic law?
When a graph goes a straight line
Voltage is proportional to current
What is non oh mic?
When a graph is not straight and has no correlation
What is parallel circuit?
Circuit is separated
What is series circuit?
Circuit is joined without getting split or with branches
What is the difference between a thermistor and LDR?
Thermistor is temperature dependent resistor
LDR is light dependent resistor
What are resistors used for?
Control flow of current in an electrical circuit
A component that is non oh mic?
A filament bulb
What is meant by direct current?
Current flows in one direction only from positive to negative
What is a fuse?
A fuse is a safety devices that protect against these faults
What does a fuse do?
A wire is in a fuse that melts if a current in a circuit gets too hot resulting in overheating. It will melt if this happens so
What does an earth wire do?
It will cause the fuse to blow so that the current stops flowing and it makes it safe
What does a circuit breakers do?
It disconnects electricity if there is a difference in the current flow
