Chapter 5.2 Flashcards
Electric resistance definition and formula
The potential difference across a conductor’s ends divided by the current passing through it
R = V/I
Ohm’s law
When the temperature of most metallic conductors is kept constant, the current through the conductor is proportional to the potential difference across it
What devices will deviate from Ohm’s law?
Filament lamps at high currents
Diodes
Thermistors
Relationship between resistance, length of wire and cross sectional area
R = pL/A
p = resistivity of wire
Power dissipated in a resistor formula
P = IV
Variations of the electrical power formula
P = IV = RI^2 = (V^2)/R
emf
The work done per unit charge in moving charge across the battery terminals
What are the requirements for charge to be pushed in order to drift in the same direction?
An electric field which requires a source of potential difference
Total resistance if three resistors in series
Rtotal = R1 + R2 + R3
Kirchhoff’s current law (first law)
Total current in equals total current out
Adding resistors in series __ the total resistance of a circuit and adding resistors in parallel __ the total resistance
Increases, decreases
Kirchhoff’s loop law (second law)
Change in voltage in a circuit is zero
Ammeter
An instrument that measures the current through a resistor, connected in series to the resistor
Resistance of an ideal ammeter
Zero resistance
Voltmeter
Measures the potential difference across a device, connected in parallel to the device
