electrical charge and currenr Flashcards
(40 cards)
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
what does resistance slow down
flow of electrons
what happens in a series circuit when u increase the amount of resistors
the total resistance increases so the electrons flow slower
what happens in a parallel circuit when u increase amount of resistors
the total resistance decreases so the flow of electrons is faster because voltage is same but current increases
why does total resistance decrease in parallel circuit
both resistors have the same potential difference but adding a extra loop, the current has more than one direction to go in. this increases the total current. an increase in current means a decrease in total resistance
what isn’t an ohmic conductor
bulb and diode
what is an ohmic conductor
resistor
what is OHM’s law
the potential difference (voltage) across an ideal conductor is directly proportional to the current through it when the temperature is constant
components that follow this law are called ohmic conductor
what happens to atoms in filament bunk when temp increases
atoms in metal filament vibrate more as the temperature increases. they resists the passage of the electrons through the filament more. the resistance increases as its temp increases
