Transcript Electricity - science

Electricity
Current
Voltage
Resistance
Current, Voltage, Resistance characteristics
AC DC
Plugs
Earth
Fuses
Power
Current
• Current is the amount of charge flowing
past a point in a given time
Current (A) = Charge (C) / time (s)
Current read by an ammeter –
connected in series
Potential Difference
• Voltage
• Potential difference is the energy given
to or given by a charge when it passes a
component.
PD (V) = Energy (J) / Charge (C)
PD is taken by a voltmeter and is
connected in parallel with the
component.
Resistance
• Resistance is the volts per amp for a
component.
• How many volts are needed to push a
current of so many through a
component.
Resistance (Ohms) = PD (V)/ Current (A)
• Circuit models
• Circuit diagrams
• Resistor models
IV Characteristics
• Resistor
• Bulb
• Diode
Resistors
• Thermistor
• LDR
• review
Mains Elec
• PHET
• AC DC
• Period and frequency
Plugs
Fuse
• A Fuse is a piece of wire with a low
melting point
• If there is a fault in the electrical
appliance and the current goes up it
could damage the wiring in the appliance
• But if a fuse is installed, this will melt
(or “blow”) and break the circuit
• So a fuse is used to protect the
appliance – not necessarily to protect us
from electric shock
Earth
• What on Earth does it do?
• VdG
Earth
• No Earth – No Fault
Earth
• No Earth - Fault
Earth
• Earth – no Fault
Earth
• Earth - Fault
Power
• Power = work done / time taken
• Lifting stuff
Electrical Power
• Electrical power is the electrical work
done in a given time.
Power (W) = current (A) x voltage (V)