Electrostatics&sMagnetism, Circuts Flashcards
Define insulator
Materials that do not transfer or move charge, have localized areas of charge. Non metals
What materials are insulators
non metals
Define conductor
A material that has an even distribution of charge and allows for the transfer of charge. Metals
What type of materials allows for the transfer of charges
Conductors
Describe Coulombs Law
it quantifies the magnitude of an electrostatic force between two charges
What represents electrostatic force?
Fe
What is Columbus law equation?
Fe=Kq1xq2/r2
What is the relationship between electrostatic force and distance?
Inverse, if distance is doubled, force is cut by 1/4
If the distance between two charged is doubled what happens to the electrostatic force?
It is cut by 1/4
What is an electric field?
A force generated by every charge and exerts a force on other charges brought into the field
What is the electric field equation?
E=Fe/q=kQ/r2
What equation is this: E=Fe/q=kQ/r2
Electric field
In which direction do field lines go for a positive source charge?
Outwards
In which direction do field lines go for a negative source charge?
Inwards
In which direction will positive test charges move in respect to the source charge field lines?
Same direction
+SC lines move outwards and opposites repulse
-positive TC follows -SC lines because -SC lines move in and opposites attract
In which direction will negative test charges move in respect to the source charge field lines?
Opposite
-SC lines move in, -TC will move out (repulsion)
+SC lines move out, -TC will move in (attraction–against SC lines)
What is electric potential energy?
The amount of work needed to bring a TC from a far position to one closer to to SC
What is the electric potential energy equation ?
U=kQq/r
Define electric potential
The ratio of the magnitude of a charges electric potential energy (U) to the magnitude of the charge itself (q)
The closer two opposite charges get the more ______ the potential energy and ______ in stability
Decreases, increases
There is a ______ in electric potential energy when opposite charges get closer together
Decrease
Two like charges will have a ______ in potential energy the closer they get
Increase
The closer two like charges get the more ______ the potential energy and ______ in stability
Increase, Decrease
The closer two like charges get the more ______ the potential energy and ______ in stability
Increase, Decrease
What is the electric potential equation?
V=U/q
V=kQq/r
What is electric potential measured in?
Volts
What are the units for Volts
1V=1C/J
Voltage is also known as
potential difference
For a positive source charge voltage is ________
Positive
Electric potential is _______ proportional to the distance from source charge
Inversely
A positive test charge will move from a position of ______ to ______ electric potential causing a decrease in electric potential energy
High to low
In which direction do positive test charges move with respect to source charge
With direction of source charge
A negative test charge will move from a position of _____ to _____ electric potential.
Low to high
What is an equipotential line?
A line where the potential at every pain is the same, the potential difference (voltage) is zero
A ______ results from two equal and opposite charges being separated by a small distance from each other
Electric dipole
The product of charge and separation distance is defined as the
Dipole Moment
What is the equation for dipole moment?
p=qd
Magnetic field strength is measured in _____ and _____
Tesla and Gauss
1 Tesla=_____ gauss
10^4
Diamagnetic materials
- made of atoms with no unpaired electrons
- slightly repelled by magnet
Paramagnetic Materials:
- have unpaired electrons
- no magnetic dipole
- no net magnetic field
- weakly magnetized
Ferromagnetic material characteristics
- unpaired electrons
- no net magnetic dipole
All moving charges create a _____ field
Magnetic
Magnetic fields are created by
all moving charges
A straight wire carrying a charge has an electric field that is ____ to the wire
Perpendicular
How do you calculate the magnetic field perpendicular to a wire?
B=(mu)(I)/2Pir
Describe the right hand rule to determine direction of magnetic field vectors?
Point thumb in direction of current
Close hand
Direction of fingers act as circular fields
Current is a flow of ____ charge, but ____ charge is actually moving
Positive, negative
What is metallic conductivity?
Conductivity that relies on the free movement of electrons in metallic bonds
_____ conductivity depends on the ion concentration of a solution
Electrolytic
A solution with high ion concentration has ____ conductivity
high
A solution with low ion concentration has ____ conductivity
Low
The concentration of ions and conductivity are ______ proportional
Directly
The flow of charge between two points is
Current
The magnitude of current is
the amount of charge passing thru a conductor per unit of time
What is the equation for current?
I=Q/t
Electrons moving from low electric potential to high electric potential causes a ______ in electric potential energy
Decrease
What is electric potential energy?
the work required to bring a test charge from farm away to a position close to the source charge
Describe Kirchoff’s Junction rule
at any point in a circuit, the sum of currents directed to that point equals the sum of currents directed away from that point
I (into)=I (out)
What is Kirchoff’s Loop Rule
in a closed loop the sum of voltage sources is always equal to the sum of voltage (potential) drops
V(source)=V(drop)
Define resistance
opposition to the flow of charge
Electrons moving from low to high energy causes a _____ in potential energy
decrease
Materials that do not offer any resistance are called
conductors
Materials with high resistance are called
Insulators
_____ have high resistance
Insulators
______ do not have any resistance
Conductors
Materials that provide a medium of resistance are called
Resistors
Conductors allow the free passage of electrons
True
Resistance of a resistor is _____ proportional to the length of the resistor
Directly
As the length of the resistor increases the resistance of the resistor
Increases
What is resistivity
intrinsic resistance
Why is resistance increased with the length of the resistance?
the charge has to flow a grater distance
Cross sectional areas is ____ proportional to resistance
Inversely
Increasing CSA ______ resistance
Decreases
How does temperature affect resistance?
Increases resistance
T/F: Temperature is linearly proportional to resistance
True
Electrical resistance results in _____ loss which reflects a drop in _______ _______
energy, electric potential
Which equation is used to calculate voltage drop?
V=IR
Describe Ohms Law
For a magnitude of resistance, the voltage (electrical potential) drop across the resistor is proportional to the magnitude of the current
What is the definition of power?
The rate at which energy is transferred or transformed
What is the general equation for power?
P=W/t
P=Delta E/t
What is the equation for electric power?
P=IV=I^2R=V^2/R
What is the definition of electric power?
The rate at which energy is dissipated by a resistor
Voltage supplied to a circuit is reduced by from its emf vis reduced by
Internal resistance
How do you calculate the actual voltage that is supplied by a cell to a circuit including the internal resistance?
V=E(cell)-ir(int)
where E is the emf of the cell
i is current
r(int) is internal resistance
Current must pass through all resistors when they are in
series
Current divides and passes through resistors separately when they are in
parallel
Resistance sum increases as
more resistors are added
Voltage drops are additive so for R1, R2, R3, the voltage drop is
V1 + V2 + V3
How do you calculate resistors in series?
R1 + R2+ R3…
When resistors are in parallel, resistor sum ______
decreases
T/F: Voltage drop at each resistor in parallel is the same at each resistor
True
Current is the greatest thru the path with
least resistance
Putting resistors in parallel reduces
equivalent resistance
How to calculate resistors in parallel
1/Rp=1/R1+1/R2
How do you find the current thru each resistor in parallel?
First find current flowing thru whole circuit (1/Rp)
Use Ohms law to calculate current
______ have the ability to store and discharge electrical potential energy and are characterized by their ability to hold charge at a particular voltage
Capacitors
What is capacitance of a capacitor?
The ratio of the magnitude of the charge stored on one plate to the potential difference across the capacitor
What is the capacitance equation?
C=Q/V
What is the unit for capacitance?
Farad (1F=1C/V)
The separation of charges sets up a __________ between plates with parallel field vectors
Uniform Electric Charge
What is the equation for electric field in capacitor?
E=V/d
What is the equation for potential energy stored in a capacitor?
U=1/2CV^2
What is the equation for potential energy?
U=mgh
What is the equation for kinetic energy?
K=1/2mv^2
Capacitors store energy in the form of
charge separation
Material that increases capacitance
dielectric material
In isolated capacitors dielectric materials the increase in capacitance is due to a _____ in voltage
decrease
The dielectric constant of a material is a measure of
Its insulating abilities
When a dielectric material is in a charged capacitor in a circuit the charge on the capacitor
Increases
The dielectric material in a circuit increases the capacitor charge stored causing an increase in
capacitance
An increase in capacitors in series _______ capacitance total
Decreases
The equation for calculating capacitance for capacitors in series:
1/Cs=1/C1+1/C2
For capacitors in seres, the total voltage is the
sum of individual voltages
Capacitors wired in parallel produce a resultant capacitance that is equal to
the sum of individual capacitances
Capacitance of capacitors in parallel ______ as more capacitors are added
Increases
The equation for capacitance of capacitors in parallel. is:
Cp=C1+C2….
How does dielectric material impact capacitance
It increases capacitance
How does dielectric material impact voltage
If capacitor is isolated: voltage will decrease
If capacitor is in circuit: voltage will stay constant
How does dielectric material affect charge?
If isolated: charge stays constant
If in circuit: stored charge will increase
What are meters?
Devices that measure circuit quantities
Describe the function and characteristics of ammeters
measures current in a point in a circuit
inserted in series
zero resistance
Describe the function and characteristics of voltmeters
measure voltage drop
inserted in parallel
have large resistance
Describe the function and characteristics of ohmmeters
measure resistance
inserted around a resistive element
self powered with negligible resistance
