Define Electric Field Strength
Electric field strength at a point in space is the force per unit positive charge
Define Magnetic Flux Density
a measure of the strength of a magnetic field at a given point, expressed by the force per unit length on a conductor carrying unit current at that point.
One Tesla is the uniform magnetic flux density which, acting normally to a long straight wire carrying a current of 1 ampere, causes a force per unit length of 1Nm-1 on the conductor.
Define Magnetic flux
magnetic flux = magnetic flux density x area (perpendicular to field direction)
B x A (normal to B). Magnetic flux=magnetic field x Area
Define The Weber
One Weber is equal to one Tesla metre²
Define Magnetic Flux Linkage
The change of magnetic flux linkage is equal to the product of the change in magnetic flux and the number of turns N of a conductor involved in the change in flux
Capacitance = charge per (unit) potential differences
Ratio of charge to potential for a conductor
Define The Farad
coulomb per volt
A farad is the charge in coulombs which a capacitor will accept for the potential across it to change 1 volt
Define The Time Constant Of A Circuit
Time for the charge to have decreased to "1/e" of its initial charge
Define Proton Number
The number of protons found in the nucleus of an atom
Define Nucleon Number
The mass number, the sum of the number of neutrons and protons in an atomic nucleus
Isotopes are different forms of the same element which have the same number of protons but different numbers of neutrons in their nuclei
Define Activity (Radioactivity)
Spontaneous emission of a stream of particles or electromagnetic rays in nuclear decay
Define The Decay Constant
The probability of decay of a nucleus per
Reciprocal of decay time
Define Half Life
The half-life of a radioactive nuclide is the time taken for the number of un-decayed nuclei to be reduced to half its original number
Define Binding Energy
The energy equivalent of the mass defect of a nucleus. It is the energy required to separate to infinity all the nucleons of a nucleus
Define Binding Energy Per Nucleon
Binding energy per nucleon is defined as the total energy needed to completely separate all the nucleons in a nucleus divided by the number of nucleons in the nucleus
Power per unit area(W/m²)
Define The Distance Measured In Astronomical Units (AU)
The astronomical unit is defined as the radius of the circular path round the sun followed by a body in 365.25 days
Define The Distance Measured In Parsecs (pc)
Distance from a base length of 1 AU that subtends an angle of 1 (arc) second
Define The Distance Measured In Light-Years (ly)
The distance travelled by electromagnetic radiation (light) in one year
Define Critical Density
The average density of the universe
- Above which the universe will collapse (closed universe)
- Below which the universe will expand forever (open universe)
- If the density is equal to the critical universe get a flat universe.
State that electric fields are created by electric charges
Electric charges exert forces on each other when they are a distant apart. An electric field is a region of space where a stationary charge experiences a force
State and use Fleming’s left-hand rule to determine the force on a current conductor places at right angles to a magnetic field.
If the first two fingers and thumb of the left hands are placed at right angles then the first finger is in the direction of the field, the second in the direction of the current and the thumb in the direction of motion
State and use Faradays Law of electromagnetic induction
Induced e.m.f is proportional to the rate of change of (magnetic) flux
State and use Lenz’s law
The direction of the induced e.m.f is such as to cause effects to oppose the change producing it
State and use the equation for the total capacitance of two or more capacitors in parallel
State and use the equation for the total capacitance of two or more capacitors in series
1/Ct =1/C1+1/C2+1/C3 ......
State the quantities conserved in a nuclear decay
The charge, the total number of neutrons and protons, total energy, the total momentum of the system and the total lepton number.
State that there are two types of β decay
β- decay produces an emission of electrons. (Electron) antineutrinos are produced.
A β- particle IS an electron.
β+ decay produces an emission of positrons. (Electron) neutrinos are produced.
A β+ particle IS a positron.