Electricity and Magnetism Flashcards
A particle must always have a
“q” a charge
In which direction does the electric field always move
The electric field will always move in the direction of a positive test charge’s force it would feel
Formula for force of an electric feild
F = qE
Used in any sitation where you have an electric field
Units for the electric force
Columns (C)
Coulomb’s Law
Formula for attraction between 2 charges only
F = k(q1q2/r^2)
Analogous to the Fg formula
Charge of an electron
1.6 x 10^-19C
Formula for electric field due to a point charge
E = k(q/r^2)
Formula for Potential Voltage
V = k(q/r)
Formula for potential energy
P.E. = qV
Can also be referred to as “U”
Objects will move how in terms of potential energy
Objects move from high potential energy to low potential energy
Keep in mind that with negative charges they move towards higher voltages because
They are becoming more negative and there for moving towards lower potential energy
When using Coulomb’s law if charges are the same
We only calculate one electric field, other wise we’d calculate two different ones
Formula for Ohm’s law
V = IR
Formula for current
I = q/t
Units are Amphs
A current flows like
The imaginary flow of positive charges
How does the current behave for elements or resistors in a series
They have the same current
How does the current behave for elements or resistors in parallel
They have the same potential “drop”
Formula for resistance
R = ρ(L/A)
Formula for resistors in series
Req = R1+R2+R3+…
Formula for resistors in Parallel
(1/Req) = 1/R1 + 1/R2+…
Formula for Power
P = VI = I^2R = V^2/R
V being the Voltage drop across resistors not the total voltage
Kurkoff’s Junction Rule
Any current flowing in must also flow out
Kurkoff’s Loop Rule
In any loop around a circuit; any potential increase will be balanced by a potential decrease
Shortcut when you only have 2 resistors
R1 x R2/ R1+R2
Formula for rms voltage
Vrms = Vmax/√2
Formula for rms intensity
Irms = Imax/ √2
Formula for capacitance
C = Q/V
Units are Farad’s
Paralel Plate Capacitor Formula
C = kε0(A/d)
k= dielectric constant
Formula for potential energy stored in a capacitor
P.E. = 1/2 CV^2
Formula for capacitors in a series
1/Ceq = 1/C1 + 1/C2 +…
Formula for capacitors in parallel
Ceq = C1 + C2 + …
What happens to the charge, the voltage and the intensity when charging
Q & V start from rest and slowly rise up to a max amount.
Intensity starts at max and decreases
What happens to charge, voltage and intensity when discharging
Q & V & I start from max and decrease
Formula for a charged particle moving through a magnetic field
F = qvBsinθ
V = velocity B = Magnetic field θ = angle between v & B
Right hand rule for a charged particle moving through a magnetic field
Thumb = v Fingers = B Palm = Force
For negative charges the force comes out of
The back of your right hand’s palm
Formula for current-carrying wire in a magnetic field
F = ILBsinθ
Right hand rule for current carrying wire in a magnetic field
Thumb = I Fingers = B Palm = Force
Magnetic field due to a current carrying wire formula
B = μoI/2πr
Right hand rule magnetic field due to a current carrying wire
Thumb = I
Fingers (curled) = B
