Ch12 and ch13 Electricity Flashcards
What is electric current?
The rate of flow of charge
What is potential difference?
Work done moving a unit charge between two points in a circuit
V=W/Q
What is resistance?
How difficult it is for current to flow
R=V/I
What is an ohmic conductor?
Ohms law
Current directly proportional to pd if physical conditions constant
How do you measure pd across a component?
Why?
Voltmeter in parallel
Resistance is very high
How do you measure current in a circuit?
Why?
Ammeter in series
Resistance is very low
What is a diode?
Only allows current to flow in one direction
What is an LDR?
Semiconductor sensitive to light
As light intensity increases, resistance decreases
What is resistivity?
How easily a material conducts electricity
P= (RA)/L
A is cross sectional area and L is length of wire
What is a superconductor?
A material that has zero resistivity below critical temperature.
What is Kirchhoff’s First Law?
All current going into junction is equal to current leaving the junction
Charge is conserved
What is Kirchhoff’s Second Law?
For any loop the sum of pds equal to total EMF
Energy is conserved
What is power?
Rate of energy transfer or work done
What is the purpose of a potential divider?
Provide variable resistance
Provide a constant specific pd
