P2 Fc Before Exam Flashcards
Define electromotive force
Electro motor force is the work done per unit charge
How do we find the maximum EMF from a magnetic flux linkage against time graph
Draw a tangent where the gradient is the greatest as EMF is proportion to the rate of change of flux linkage then find the gradient of the tangent
Define a Tesla
The flux density which produces a one newton force on a 1 m long wire carrying one of current flowing perpendicular to the field
Describe the path of a charged particle entering at right angle to a uniform magnetic field
Circular
Explain the two rolls of the core in a transformer
The core directs the magnetic field round to the secondary coil and ensures that more of the flux from the primary coil linked with the secondary coil
Explain two features of the core and a transformer which aids the efficiency of the transformer
It is made from soft iron so that it can be easily magnetised and demagnetised and it is laminated to increase resistance and reduce current
Define electric potential at a point
The work done per unit +ve charge on an object to bring it from infinity to that point
How do you find the electric potential between 2 charges at the midpoint
Find the electric potential for one at the midpoint, do the same for the other
Then add the two potentials
Remember the charge for an electron = - 1.6…
Explain why a high speed proton is required to fuse with a nucleus
The proton is repelled by +ve nucleus therfore a high speed proton will gat close enough to nucleus to fuse
How do protons stay within a nucleus
Due to the strong nuclear force that acts on the protons and is attractive
What material is required to absorb a beta particles?
3 mm aluminium
What is a photon
A discrete packet of electromagnetic energy
Describe a reasonable value for the half-life of the tectinium 99M isotope which is used as a medical tracer
Six hours
Tech technetium- 99m has a half-life of six hours calculate the fraction of the initial number of nuclei that remains after 24 hours
Fast find the number of half-life in 24 hours which is( 24 divided by 6)
Then do 0.5 to the power of the number of half life which gives you a 16th to show the fraction of the initial number of nuclear that remains?
Define activity
The rate of decay of a nuclei
Give an equation to find the initial rate of energy emission of a substance
E of photon x activity
A stationary wave is formed in a tube with is closed on one end and open in the other. The fundamental frequency is 120 Hz what is the next possible harmonic?
The next harmonic in an open tube and enclosed end would have to be an odd multiple of the fundamental frequency therefore the next odd multiple is three therefore the next frequency is 360 Hz
In a circuit, there is a voltage supply at one end and a battery at the other end these supplies are arranged such that the negative terminals face each other and positive time to face each other therefore they are pushing current in different direction. How do you find the net voltage?
You have to subtract the Volle Tages from each other as they are travelling in opposite directions
Define electric potential at a point in space
The work done per unit charge in bringing a positive charge from Infiniti to that point
How do you calculate the relative permeability of a material and the permeative of material?
Relative permittivity
C=ee0A/d
Permittivity
C=eA/d
Give the behaviour of the strong nuclear force
It acts between neons it is attractive from 0.5 fm to 3 fm and as repulsive up to 0.5 FM and it has a short range
Describe what happens to the quarks during beta minus decay
Beta decay is when a neutron turns into a proton therefore down Quirk becomes an up quark
What is the binding energy per nucleon of h2,1
1.1 mega electron volts per nucleon
Explain why high temperatures are required for fusion
The protons repel each other therefore at high temperatures particles have more kinetic energy and can get close enough to fuse
State kirchoffs of second law and the physical quantity conserved
The sum of the EMFs is equal to the sum of the potential difference in a loop and energy is conserved
A displacement against time graph is plotted for a wave with a period T what would the graph for a wave with a period of T/2 look like
It would be the exact same graph but opposite therefor it is flipped on the x axis
When is a beta minus particle emitted and when is a beta plus pass omitted?
Beta minus particle is emitted when the nucleus has too many neutrons
a beta plus particle is omitted when the nucleus has two few neutrons
What does the atomic mass unit equal to in mega electron volts
= u=931.5 MeV
An oil drop is stationary between two oppositely charged plates that have an electric field when the potential difference between the plate is 200 V the magnitude of the vertical electric force is equal to the weight. The potential difference is now increased to 600 V by what factor does this electric force increase?
The voltage has tripled therefore the electric force will also triple and the weight of the oil drop will remain constant
