Circuits and resistance Flashcards
What is current?
What is the unit?
The flow of electric charge round a circuit.
Amps, A
When only will current flow?
Through a component if there is potential difference across the component
What is potential difference?
What is the unit?
The driving force that pushes the current around
V, Volts
What is resistance?
What is the unit?
Resistance is …
anything in the circuit which slows the flow of electricity down
ohm, the o with feet stuck out out the outsides
futile
What is the rule about resistance across a component?
The greater the resistance across a component the small the current that flows (for a given p.d across the component)
Current is the … of flow of …
What is the equation for current?
rate of flow of charge
Current (A) = charge (C) / time (s)
What is a charge measured in?
More charge passes around the circuit when a bigger … flows.
Coulombs, C
current
P.D is the …. …. per Coulomb of ….. that passes bewteen …. …. on an electrical circuit
work done, charge, two points
What is the formula for P.D?
So the P.D across an electrical component is the amount of …. …. by that electrical component per … … ……
P.D = work done / charge
energy transferred, per unit of charge
Voltage and P.D ….
mean the same thing
What does the symbol for a cell look like?
Horizontal line joint to a vertical like a sideways T, with another T the opposite way round, head to head with a gap, but T2 is smaller and thicker, just the top of the T not the wire
What does the symbol for a battery look like?
Horizontal T, with another T the opposite way round, head to head with a gap, but T2 is smaller and thicker, just the top of the T not the wire, the wire is dashed to form the stand of the next T that meats another thick T that continues onto the circuit.
What does an open switch look like?
two circles with a stick like a gate between them that is open, not touching the second dot
What does a closed switch look like?
two circles with a stick like a gate between them that is resting on the second dot, in contact, and closed
What does a filament lamp diagram look like?
A circle with a black X through the middle
What does a fuse diagram look like?
a rectangle on the wire line which you can see running through it
What does an LED, light emitting diode diagram look like?
a circle with a triangular arrow point in the direction of current low with a vertical line at its tip, inside the circle, with two arrows outside of the circle pointing upwards to represent light.
What does a resistor diagram look like?
the wire with a blank rectangle on it. You CAN’T see the wire running through it.
What does a variable resistor diagram look like?
a resistor, a blank rectangle, with a straight arrow going from left to right across it.
What does an ammeter diagram look like?
A circle with a capital A in it
What does a voltmeter diagram look like?
A circle with a capital V in it
What does a diode diagram look like?
a circle with a triangular arrow point in the direction of current low with a vertical line at its tip, inside the circle
What does a light dependent resistor (LDR) diagram look like?
a circle on the line, the line goes inside the circle but stops at the square inside, the resistor, then comes out the other end. There are two arrows outside of the circle pointing in representing light.
What does a thermistor diagram look like?
a blank rectangle, with a line across it that runs parallel to the box (below it) for a little bit then goes up like the ticks do, across the themristor