Summary physics ch1 Electricity
1.1 Generating electrical energy
Electrical energy must always be generated. To do so, we apply Faraday’s Law.
A changing magnetic field will induce a current in a conductor.
Something (steam, moving water or what have you) allows a turbine to spin, generating
electrical energy via Faraday’s Law.
All power outlets in Europe are 230 volts.
The amount of energy a device consumes per second is called its ‘power’ or sometimes
‘wattage’.
P=U ∙ I p is power (w), u is voltage (V), I is current (A).
A device with a high power rating will consumes more energy per second than a device
with a lower power rating.
The amount of electrical energy consumed by a device is determined by its power and
operating time.
E = P ∙ t e is energy (j), p is power (w), t is time (s)
Kilowatthour= 3,600,000 J, 3.6 MJ. When using the kWh, instead of watt and seconds use
kilowatts and hours.
1.2 Transporting electrical energy
When current passes trough a wire, some of the electrical current turns into heat.
Voltage of the mains is often still too much for a device, these types of devices then need a
transformer that steps down the voltage. It is often part of the plug or the bulb.
Transformer= there will go a current trough the primary coil, it will
become an electromagnet. As a result the iron core becomes
magnetized also and then the secondary coil also which makes a
voltage where the appliance works on.
Formula for calculating turns.
Up and Us are the voltages in primary and secondary coils.
Np and Ns are the number of turns in primary/secondary coils.
Formula for calculating power supplied by the secondary coil=
Up ∙ I p = U s ∙ I s
Up and Us are the voltages in the primary/secondary coils in volts.
Ip and Is are the currents in primary/secondary coils in amps.
1.1 Generating electrical energy
Electrical energy must always be generated. To do so, we apply Faraday’s Law.
A changing magnetic field will induce a current in a conductor.
Something (steam, moving water or what have you) allows a turbine to spin, generating
electrical energy via Faraday’s Law.
All power outlets in Europe are 230 volts.
The amount of energy a device consumes per second is called its ‘power’ or sometimes
‘wattage’.
P=U ∙ I p is power (w), u is voltage (V), I is current (A).
A device with a high power rating will consumes more energy per second than a device
with a lower power rating.
The amount of electrical energy consumed by a device is determined by its power and
operating time.
E = P ∙ t e is energy (j), p is power (w), t is time (s)
Kilowatthour= 3,600,000 J, 3.6 MJ. When using the kWh, instead of watt and seconds use
kilowatts and hours.
1.2 Transporting electrical energy
When current passes trough a wire, some of the electrical current turns into heat.
Voltage of the mains is often still too much for a device, these types of devices then need a
transformer that steps down the voltage. It is often part of the plug or the bulb.
Transformer= there will go a current trough the primary coil, it will
become an electromagnet. As a result the iron core becomes
magnetized also and then the secondary coil also which makes a
voltage where the appliance works on.
Formula for calculating turns.
Up and Us are the voltages in primary and secondary coils.
Np and Ns are the number of turns in primary/secondary coils.
Formula for calculating power supplied by the secondary coil=
Up ∙ I p = U s ∙ I s
Up and Us are the voltages in the primary/secondary coils in volts.
Ip and Is are the currents in primary/secondary coils in amps.
