electrical charge and currenr Flashcards
what is current
flow of electrical charge (flow of electrons)
what is a resistor
slows down flow of electrons / charge
what is a diode
allows current to flow in one direction only protect the components of the battery is the wrong way round
what is an LED
Special type of diode that glows when electricity passes through it
what is a thermistor
thermistors are used as temp sensors, their resistance decreases as the temperature increases. at low temp the resistance of a thermistor is high and little currently can flow through them
at high temp the resistance of a resistor is low and more current can flow through them
what’s a LDR
detects light levels. their resistance decreases as light intensity increases. in the dark and at low light levels resistance of an LDR is high and little current can flow through it. in bright light , resistance of an LDR is low, and more current can flow through
what do u use to measure current
ammeter
equation for total charge
Q=IT
I= current (amps ) T= time (seconds ) Q= charge (coulombs)
what is potential difference
a cell supplies energy to a charge to move it through the circuit and produce a potential a potential energy difference at one end of the circuit compared to the other , this creates a PD
what conclusion can u make abt current in a series circuit
current is the same
what conclusion can u make abt potential difference in a series circuit
potential difference is shared
what conclusion can u make abt current in a parallel circuit
current is shared
what conclusion can u make abt potential difference in a parallel circuit
potential difference is the same
what does current through a component depend on
- resistance of component
- potential difference across component
equation for potential difference
V=IR
V= potednail diff (voltage) I= current (A) R= resistance
how does increasing the length or wire change the current
increasing length of wire decreases the current as it takes longer for the electrons to flow but the potential difference increases so the resistance is higher
as length of wire increases the resistance increases. resistance is directly proportional to length of wire