Current Electricity Flashcards
What is the definition of current?
The rate of flow of charge
(I = change in Q/ change in t)
What is potential difference
Work done to move a unit charge between 2 points in a circuit
(V = W/Q)
What is resistance?
How difficult it is for a current to travel through an appliance
(R = V/I)
What is an ohmic conductor?
A conductor where the current is directly proportional to potential difference
Why does an increase in current in a filament lamp lead to an increase in resistance?
As current flows, some electrical energy is wasted as heat which causes the metal ions to vibrate. This leads to more collisions so a larger resistance
What is a diode?
An appliance that only allows current to flow in 1 direction
What is a Light Dependent Resistor (LDR)?
A semi conductor that is sensitive to light, as intensity increases, resistance decreases
How do thermistors work?
Similar to LDR but with temperature instead of light inensity
What is resistivity?
Resistance of a 1m cylinder with a cross sectional area of 1m^2
(P = RA/L)
What is a super conductor?
A material with a reistsivity of zero, at or below a critical temperature
