Electicity Flashcards
what is electrical current
The flow of electrical charge
State the equation that links charge current and time
Charge(Coulombs)= Current(Amperes) x Time( seconds)
Q= I x T
what is the value of current at any point in a single closed loop
current is the same at all points in a closed loop
What two factors does the current in a circuit depend on
Potential difference
Resistance
Equation for potential difference
V= I R
What is an ohmic conductor
A conductor for which current and potential difference are directly proportional
Resistance remains constant as current changes
Temperature must be constant
List 4 Componenets for which resistence is not constant as current changes
Lamps
Diodes
Thermistors
Light dependent resistors
What happens to the resistance of a filament lamp as the temp increases
Resistance increases
Ions in metal have more energy causing more collisions with electrons as they flow through the metals creating greater resistance to current flow
What is different about current flow through a diode
The current only flows in one direction
Resistance is very high in other direction prevent current flow
What happens to the resistance of a thermistor as temp increases
Resistance decreases
Give two examples of when a thermistor may be used
In a thermostat
In a freezer
What happens to the resistance of a LDR as light intensity decreases
Resistance increases
Give an application for a LDR
Street lights
when loght levels become too low the light gains sufficient current to turn on
