exam revision Flashcards
Two uses of ultraviolet
Killing bacteria such as water purification
to decet counterfeiting of money
Two dangers ultraviolet
Cell damage
Sunburn
Eyedamghe
What is the charge of a alpha particle
2+
What is the charge of of particle beta
-1
Suggest why alpha radiation is more iosnisinhg than beta or gamma radiation?
Charge is larger and mass is larger
Why is doctor reading never constant (radioactivity)
Radioactivity is random
Explain why radioactivity sample reduces with time?
The activity is due to the nucleus decaying and after some time they are fewer radioactive nuclei
Decrease how a teacher could measure the activity of a radioactive source?
Use a geiger counter to measure the background radiation, the teacher should wear gloves and control the experiment by putting the source near the detector. Should repeat and find average. Measure answer in Bq
Explain how to use radioactive to find age of rock?
There is a know proportion
Measure the proportion of the activity now
Compare the activity to the original activity
Hence determine the number of half-lives elapsed
What is the maximum range of beta particle
50CM
How nuclear fission leads to a chain reaction:
Nucleus splits
Reralsing neutrons
Which hit different uranium nuclei
Explain form that this energy takes nucleus fission
Kinetic energy of particles of fission products
wave speed frequency and wavelength
wave speed = frequency x wavelength
time period frequency
frquecny = 1/time period
sin I sin r and n
n = sin I/sin r
sin c and n
sin c = 1/n
exam experiment speed of sound
speed = distance divided by time
stand 50m away from the wall and time how long it takes for the echo to come back
time how long it takes the echo to come back
repeat the experiment three times and find averages
Thermal velocity
When an object falls its weight causes it to accelerate towards the ground.
Resistive forces act on it in the opposite direction to its motion.
As the object speed increase the resistive force increases until these balance the downwards force of the objects weight
So there is no resultant force so it travels at a constant
what is the relationship between frequency of sound wave and the pitch of the sound
the higher the frequency the higher the pitch
earth wire
there is a current in the wire so it discharges the object
experiment charge testor
deflect gold leaf electroscope
why does charge remain
there is insulation
Hooke law
until the elastic limit extension is directly proportional to force
