Topic 7 Flashcards
What is an electric field
A space that causes charged particles to accelerate
What is the electric field strength
The force on the charged particle by the electric field
What is the electric field strength equation
F=EQ
N = N/C * C
N=newton
C=coulomb
How can newtons second law be combined with electric field strength
F=ma AND F=EQ (same as F=Ed)
a=EQ/m (Force=efs*distance)
Each particle in a field has a potential, how can this potential be found
E=VQ
N/C = V*C
Newtom per Coulomb = Voltage * Coulomb
How do you measure the distance of a uniform electric field
d=V/E
What are equipotentials
Positions in a electric field with zero potential difference between them
What is a radial field
A region around a charged sphere where an electric field acts either towards the sphere or away from the sphere
What happens to electrical field energy as you move away from the center
Decreases and the distance between equipotentials also decrease
How does a capacitor work?
Electrons move away from the positive place through the cell and onto the negative plate
What does the area under a capacitor give?
Work done
What is capacitance
The measure of capability of a capacitor
What happens to the rate of capacitance discharge when more charge is stored?
The rate decreases
What is the time constant, and what equation is used?
The overall rate of discharge, tells us how long it will take in seconds for the capacitance to discharge by 37%
τ = RC
What is magnetic flux
Phrase used for magnetic field lines
What is a magnetic field
A space that will cause a magnetic pole to feel a force
What is magnetic flux density
The magnetic field strength in teslas
What is flux linkage
The amount of magnetic flux interacting with a coil of wire
What is quantity of flux
Φ
What is the equation for flux linkage
ΦN or ΦBAN
What is flemings left hand rule?
Thumb = motion Index = field Middle = current
Flemings right hand rule, what is it?
Thumb = motion Index = field Middle = EMF
What is the equation F=BILsinθ used for
Force on a wire or motor
What is F=Bevsinθ used for
Force on a charged particle
What is electromagnetic induction
Electrons in a wire also feel the magnetic field and will cause them to move creating an emf
What is faradays law?
Induced emf is proportional to rate of change of flux
What is lenzs law?
Moving a magnet through a wire magnetic or non magnetic will create an emf
What is AC
Alternating current is when a coil is rotated in a magnetic field creating an emf that constantly changes the direction of current
Can AC have a frequency? If so why and what els does this form
Yes because it has cycles creating a waveform
This form peak values for I and V
How is the voltage and current for AC determined
V=Vo/root2 same for I
How do transformers work?
Current passes though a primary coil which has more coils so more voltage and this generates a magnetic field in an iron core. The iron core will carry a magnetic field. The secondary coil is wrapped around less and will produce a lower voltage
Vprimary / Vsecondary = Nprimary / Nsecondary
Voltage in / V out = Number of coils left / No coils right
