Electricity And Magnetism Flashcards

0
Q

Voltage

A

Creates current

= change in electrical potential

= current * resistance

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
1
Q

Current

A

= net movement of charge

Charge/time

Direct current= current flowing in one direction
Steady voltage and current over time

Alternating current= current changes direction
Creates a sinusoidally varying voltage and current over time
Rms Voltage= voltage/(sqroot 2)
Rms current = current/(sqroot 2)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Resistance

A

=Voltage/current

Intrinsic resistance is resistivity which is denoted by p
Resistance= resistivity *(length/area)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Resistors

A

=a component in an electric current that has a specific resistance

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Series

A

Current is the same throughout the circuit

Resistance is R1+R2+…

Voltage of circuit is V1+V2

Capacitance is (1/C1)+(1/C2)+…

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Parallel circuit

A

Voltage is the same throughout the circuit

Resistance is (1/R1) + (1/R2)

Current is I1 +I2

Capacitance=C1+C2+…

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Power dissipated by resistor

A

=(current^2) * resistance

Or

= current*voltage( of that resistor)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Power of entire circuit

A

= current* voltage

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Energy

A

= power * time

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Internal resistance

A

Denoted by r

Causes the voltage between the positive and negative terminal to be different from the emf or ideal voltage

Terminal voltage V= emf- Ir

However if circuit is supplying current to the battery ( charging it) then V= emf + Ir

Ideal batteries have no internal resistance

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Capacitor

A

A pair of conductors that hold equal but opposite charges so that net charge is zero

To create a charged capacitor- hook plates to the terminals of a battery( charge will stop when potential difference between plates matches the voltage of battery-plate connected to positive terminal becomes more positive and has a higher potential)

Q= CV
Charge on capacitor= capacitance * voltage

Capacitance depends on size of plates and how far apart they are

Purpose: to create a uniform electric field and store electrical potential energy
Voltage of capacitor=electric field * separation distance

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Capacitance

A

= permittivity of free space* (area of each plate/separation)

Permittivity of free space=1/(4pi Coulomb constant)

Coulomb constant = 9 x 10^-12

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Electrical potential energy stored in capacitor

A

=0.5chargevoltage

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Discharging a capacitor

A

Recapturing stored electrical energy

Rate at which charge leaves isn’t linearly it’s rapid then a slow decrease

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Dielectrics

A

An insulator loaded between the plates of a capacitor and prevent them from touching

Presence always increases capacitance
C( with dielectric)= K(dielectric constant) * C(without dielectric)

K=1 in a vacuum or air

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Effects of the insertion of a dielectric

A

After battery disconnected- C increases by a factor of K, Q stays constant, Voltage and potential energy decreases by a factor of K( energy lost as heat)

With battery connected- PE, C and Q increases by a factor of K, voltage and electric field stay the same

16
Q

Dielectric breakdowns

A

Extra electrons on the negative plate jump across the gap to the positive plate instead of traveling down the conduction worse when the electric field strength exceeded the maximum value then the dielectric becomes ionized and acts as a conduction pathway

17
Q

Magnetic fields

A

Created by moving electric charges or currents

Magnetic force(Fb) = q( v  x  B)
Cross product of velocity of charge bad magnetic field

B for long straight wire is inversely proportional to distance from wire

Fb= qvBsin(theta)

Direction of force is always perpendicular to velocity and magnetic field
Dots mean out of page
X means into page

18
Q

Time to complete one revolution

A

= (2piradius) /velocity

19
Q

Solenoid

A

Helical coil of wires in which the magnetic field on the inside is parallel to central axis and is strongest on the central axis and gets weaker as we move away from center

Magnetic fiels is proportional to current *(number of turns/ length)

20
Q

Magnets

A

Magnetic field emanates from north to South Pole

Can’t have a pole by itself