Chapter 9: Electricity Flashcards
(27 cards)
Define electric current.
Electric current is the flow of charge carriers and is measured in ampere.
What is the direction of conventional current?
Positive to negative.z a
What is the direction of conevrntional current flow?
From positive to negative
Current is measured using what?
Ammeter
Ammeters should always be connected in?
Series
Charge of an electron
-1.6*10^-19 C
Charge of a proton
1.6*10^-19 C
Charge carried by charged particles are known as?
Quantised
Formula for current/charge
Q=It
Calculating current in a current varying conductor formula
I = Anvq
n = number density of charge carriers (m^-3)
Define potential difference across a component in a circuit.
Energy transferred per unit charge flowing from one point to another.
Potential difference is measured using a?
Voltmeter
Voltmeters must always be placed __ in a circuit
Parallel between 2 points
Potential difference/voltage formula
V = W/Q
Power formulas (3)
P = IV
P = I^2R
P = V^2/R
State ohms law resistance formula
V = IR
R = V/I
Resistance is messed in?
Ohms
State ohms law
For a conductor at constant temperature (aka constant resistance) the the current through it is proportional to the potential difference across it.
V = IR
Current against voltage graph for fixed resistor (metallic conductor) and what does gradient represent. Which is x and which is y axis
Straight line (through origin) and 1/gradient represents resistance
Current is x axis and voltage is y axis
IV characteristic/graph for a semi conductor diode
Straight line for half and then curve up
IV characteristic/graph for a filament lamp
An s shape
As temp increases what happens to resistance
Increases
Resistance formula resistivity what it depends on
R = ρL/A
ρ is resistivity is Ωm
Resistivity if metals, semi conductors and insulators respectively
Increase; insulators have the highest resistivity.
