Chapters 13 and 14: Electricity Flashcards
What is current?
The rate of flow of charge
What is the equation for current?
I = ∆Q / ∆t
What is potential difference?
The amount of electrical work done per unit charge through a component
What is the equation for potential difference?
V = W/ Q
What is electromotive force?
The amount of electrical work done per unit charge by a power supply in an electric circuit
What is the equation for electromotive force?
ε = E/Q
What is resistance?
A measure of the opposition of a conductor to electric current flowing through it
What is the equation for Ohm’s Law?
R = V/ I
What is Ohm’s Law?
The current and potential difference through an ohmic conductor under constant physical conditions are proportional
What is a thermistor?
A temperature sensitive semiconductor whose resistance increases when temperature decreases. It has a negative temperature coefficient
What is a superconductor?
A material which has zero resistivity when the temperature is decreased to, or below, the material’s critical temperature.
What are some real applications of superconductors?
Maglev trains, MRI scanners, particle accelerators
What can superconductors be generally used for?
The production of strong magnetic fields and the reduction of energy loss in transmission of electric power
What is resistivity?
The intrinsic resistance of a material independent of the dimensions of the substance
What is the equation for resistivity?
ρ= RA/l
What are three equations for power through a component?
P = IV
P = I2R
P= V2 / R
What is Kirchoff’s first circuit law?
Sum of I = 0
What is Kirchoff’s second circuit law?
Sum of emf = sum of pd
What is a potential divider?
A method of splitting a potential difference, by connecting two resistors in series. The total potential difference is split in the ratio of their resistances.
What is internal resistance?
The resistance to the flow of charge within a source. Internal resistance results in energy being dissipated within the source.
What is the equation for internal resistance?
V = ε - rI
What is the terminal pd?
The potential difference across the terminals of a power source. It is equal to the source’s emf minus any voltage drop over them source’s internal resistance.
