electricity Flashcards
(23 cards)
formula for resistance
resistance (Ω) = voltage (V) / current (A)
what does power tell us
power tells us the rate which an appliance transfers energy
What does the forumla Q=IT stand for?
Charge = Current * Time
power formula
power (W) = voltage (V) x curent (A)
What is an LDR? (Light dependant resistor)
An LDR is a resistor that changes resistance based on an amount of light
Dark conditions : high resistance
Light : low resistance
why do currents have a heating effect?
electrons move around the circuit, they collide with the ions that make up the wires and components. these collisions cause the electrons to lose kinetic energy. the kinetic energy is transferred to thermal energy, heating up the material.
What is a short circuit.
A circuit where electric current passes thorugh an unidentified, shorter pathway. This causes things such as:
Explosions called flash arcs
Melting components and starting fires
what happens if the current is higher than the fuse rating?
the wire melts which breaks the circuit
What is a parallel circuit?
A parrallel circuit is a circuit that has multiple branches that current can take. When the current meets a junction - it will split.
what is the voltage
the voltage tells us that whilst passing through the circuit how much energy has been gained or lost by each unit of charge
What is a live wire
The live wire carries the high voltage current from the mains supply to the appliance (or load). The voltage of this wire is 230V.
energy transfer in circuits formula
energy (J) = coulomb charge (C) x voltage (V)
Voltage of mains electricity?
230V
how does the resistance of an LDR change if the light changes?
low light intensity = low ldr
high light intensity = high ldr
Benefits of a parrallell circuit
When one stops working, the rest continue to work. This can be used in things such as light switches or smth
How many times does Mains electricity cycle and at water frequency?
The current alternates with a frequency of 50Hz. It does a complete cycle 50 times a second.
what is a thermistor
thermistors change their resistance based on temperature
as the temperature increases the resistor decreases
diode characteristics
diodes only allow current to pass through them in one direction (called forward bias). they have very high resistance in the other direction, and no current can flow.
What is the neutral wire?
Once the energy carried by the current has been transferred to other types, the neutral wire carries the low energy current back to the mains supply. The voltage of this wire is 0V.
what happens when the voltage is increased in a series circuit
the current increases too
what happens when you add more components in a series ciruit
increases the resistance in the circuit
current decreases
moving ammeters to different points in a series circuit
current stays the same
