electricity Flashcards
function of: cell
Provides electrical energy to charges in a circuit.
function of: battery
Provides electrical energy to charges in a circuit.
function of: diode
Allows current to flow through it in one direction only
function of: resistor
Used in circuits to set current.
function of: variable resistor
Used to vary the size of current in a circuit.
function of: fuse
A fuse melts to break the circuit if the current is too large.
function of LED:
convert electrical energy directly into light
function of: lamp
heats up when an electric current passes through it and produces light
function of: switch
turn electric circuits ON and OFF
function of: voltmeter
measure the voltage, or potential variation, between two locations
function of: ammeter
measure the current in a circuit
function of: thermistor
measure the temperature of a device
function of: LDR
detect light levels
The rate of flow of charge in a circuit =
Current
The difference in potential between two points of a circuit. Causes a current to flow =
Potential Difference / voltage.
the amount of electricity travelling through a circuit =
Charge
Anything that slows the flow of charge around a circuit.
Resistance is usually caused by electrons colliding with
ions in a material =
Resistance
A circuit with a single loop of wire =
Series Circuit
A circuit with two or more loops (branches) of wire =
Parallel Circuit
Describe the difference between a series circuit and a parallel circuit.
- A series circuit contains only one loop of wire.
- A parallel circuit contains two or more loops (branches) of wire.
charge flow (c) =
current (A) x time (s)
Potential Difference (V) =
Current (A) x Resistance (Ω)
at a constant temperature is ….
directly proportional
As the current increases, the temperature of filament increases therefore ….
the resistance of the filament lamp increases.
resistance (Ω) =
potential difference (v) / current (A)
Describe how the currents in a series circuit and a parallel circuit differ.
- Series circuit – same current at any point of the loop.
- Parallel circuit – the total current through the whole circuit is the sum of the currents in each loop
What does A.C stand for?
Alternating current.
What does D.C stand for?
Direct current.
Describe the difference between an alternating potential difference and direct potential difference.
- An alternating potential difference will go from positive to negative repeatedly.
- Producing an alternating current in a circuit.
- A direct potential difference will stay either positive or negative, but not change sign.
- Producing a direct current in a circuit.
What is the frequency and potential difference of mains electricity in the U.K?
Frequency 50Hz
Potential difference 230V
Live wire (Brown) =
Carries alternating potential difference from the supply.
Neutral wire (Blue) =
Completes the circuit.
Earth wire (Yellow/Green) =
Safety wire to stop appliance becoming live
Explain why a live wire may be dangerous even when a switch in the mains circuit is open.
A person could complete the circuit to ground getting electrocuted.
Power (W) =
Potential Difference (V) x Current (A)
Power (W) =
(current)2 (A) x Resistance (Ω)
As with any energy transfer, some energy will be transferred usefully and some energy will be ….
wasted
Energy transferred (J) =
Power (W) × Time (s)
Energy transferred (J) =
Charge flow (C) x Potential difference (V)
Step-up transformers are used to ….
Increase the potential difference and decrease the current.
Step-down transformers are used to ….
increase the current and decrease the potential difference.
Describe what would happen if two like charged particles were placed near each other.
Two like charges would repel away from each other.
A balloon is rubbed on a jumper.
The balloon becomes positively charged.
Explain why the balloon gains a negative charge.
- Electrons move from the jumper to the balloon.
- So there are more negative charges on the balloon than positive charges.
What is an electric field?
the space around a charged object that will exert a force upon another charged object that is placed there
