Extras Flashcards
Binding energy
The energy equivalent to the mass deficit when nucleons bind together to form a nucleus.
Resonance
When the driving frequency is equal to the natural frequency resulting in very large amplitudes being produced.
What is the threshold frequency?
The frequency of a photon which is equivalent to the work function
What is always the temperature of a boiling liquid?
100 degrees
What introduced uncertainty to GM tubes?
There is a dead time between successive activations.
What is the decay constant?
The probability of a given nucleus decaying in the next second.
How do you reduce harm to radioactive emissions?
Increase distance.
Use shielding around source.
Reduce exposure time.
What are the features of isotopes used for tracing?
- High activity to allow it to be detect outside the patient.
- Low enough activity so that after the procedure, others are not in danger.
How do you define the atomic mass unit?
One twelfth of the mass of carbon-12.
Why are neutrons dangerous?
1) Although they are not very ionising, they are very penetrating.
2) They are then absorbed by the nuclei, making them neutron-rich.
3) This turns them into beta-minus emitters.
Why do particles need high energy for fusion?
So that they have enough kinetic energy to overcome repulsion forces and get close enough for the strong nuclear force to act.
When is GPE or Vgrav zero?
It infinite distance from the mass
How do you cause maxima to be seen closer to the centre of the screen?
Use a light with a higher frequency.
What do you do if you are asked to work out the energy of something which heats up and then starts to boil?
1) As it heats up the mass doesn’t change so you use specific heat capacity equation.
2) When it boils the mass changes so you use latent heat.
3) Total energy is the sum of both of these.
How do you prove simple harmonic motion from a graph?
- Force directly proportional to displacement shown by straight line.
- Negative gradient shows force is directed towards equilibrium.
- Equilibrium position with no resultant force.
Why does ball with small density affect validity of free fall experiment?
Increases the air resistance to weight ratio.
Therefore air resistance won’t be negligible.
Free fall assumes only significant force is weight.
What is the absolute uncertainty of a range of values?
+ or - half the range
What is the precision of a range of values?
The number of sig figs for single readings
Why use a voltmeter and ammeter instead of ohmmeter for resistivity practical?
Because resistance is low, they have a higher precision than ohmmeter.
Criticise table
No repeats
Number of sig figs
Units?
Why should wavelength of laser be done in light room
So pupils do not dilate
How to make wavelength of laser safe
Mark maxima on paper to prevent prolonged exposure to light.
Why use a data logger and computer
Process data
Longer time
Has higher testing rate
What do you need to do for latent heat experiment
Small pieces of ice so temperature is constant throughout.
Melting point so energy is not needed to melt.
Dry so that all of the mass being added is actually ice at zero degrees.
Work at room temp to minimise transfer with surroundings
Why small oscillations in spring experiment
So spring isn’t stretched beyond limit of proportionality as this would prevent s.h.m
