Electrical circuits Flashcards
What is Current and its symbol?
Symbol = I
The flow of electric charge, measured in amperes (A).
What is Voltage and its symbol?
Symbol = V
The potential difference that pushes the current, measured in volts (V).
What is Resistance and its symbol?
Symbol = R
Opposes the flow of current, measured in ohms (Ω).
List 5 basic components
Battery: Provides voltage (energy source).
Resistor: Limits current flow.
LED (Light Emitting Diode): Lights up when current flows through it.
Wire: Conducts electricity, connecting components.
Switch: Opens or closes the circuit to stop or start current flow.
What is Ohms Law?
V = I R
Voltage equals the product of current and resistance.
What unit is charge measured in?
Coulombs
To measure current what do you have to do to a circuit?
The ammeter must be placed in series with the lamp (aka fucking next to it)
To measure energy in a circuit what do you do?
Place a voltmeter (measure of potential difference or volts) in parallel with the lamp)
What happens if you increase the resistance of a certain potential difference (voltage)?
You will reduce the current passing through e.g. if a variable resistor is adjusted to double its initial resistance, the current passing will be halved.
Rule from Ohm’s law about fixed resistors?
For a fixed resistor, the potential difference is directly proportional to the current
What is a series circuit?
Hence how is the current affected?
When components are connected in a single loop one after the other
all electrons in the loop form one current i.e. an ammeter would measure same current where ever it is placed
All source energy is shared amongst components i.e. Since
potential difference
is used to measure changes in energy, the potential difference supplied is equal to the total of the potential differences across all other components
Resistors in a series circuit?
If resistors are in a series circuit, the current must flow through all of them so the resistance is increased so:
Total Resistance = Resitance (1) + Resistance (2)
What is a parallel circuit?
Electrical components are connected alongside one another (in parallel)
Basic rules of parallel circuit?
An electron will not pass through every component of a parallel circuit so e.g. one light bulb breaks others stay on
Current will be split (as different loops) - an ammeter placed in different parts of circuit will show how current is split (so current is shared)
Potential difference (V) in a parallel circuit?
energy transferred by electrons is the same which ever path the electron follows
Potential difference supplied = potential differences across each of the parallel circuits
Resistors in parallel circuits?
Unlike a series circuit, adding more components to a parallel circuit decreases the total
resistance of the circuit. Connecting more components into the circuit in parallel causes more current to flow through the cell, not less.
(so resistance is half of a single resistor, whereas, in series circuits, it doubles)
Power formula?
Power (Watts) = current x potential difference (volts)
