p5: electric circuits Flashcards
how does a material become charged
becomes negatively charged by gaining electrons
become positively charged by losing electrons
what will two objects carrying the same type of charge do if they are brought close to each other
repel each other
what is an electric field
region of space around a charged object in which another charged object will experience an electrostatic force
what happens to the strength of an electric field as you get further from the charged object
it decreases
what is an electric current
rate of flow of charge
what are these units measured in
charge
current
time
coulombs (C)
amperes (A)
seconds (s)
what is the same at all points when charge flows in a closed loop
current
what must there be in a closed circuit so that electrical charge can flow
source of potential difference (p.d)
which 2 factors does current depend on and and what are their units
resistance in ohms (?)
p.d in volts (V)
what happens to the current if the resistance is increased but the p.d stays the same
current decreases
what is an ohmic conductor
conductor where current is directly proportional to the voltage so resistance is constant
what happens to the resistance of a filament lamp as its temperature increases
resistance increases
what happens to the resistance of a thermistor as its temperature increases
resistance decreases
what happens to the resistance of a light-dependent resistor when light intensity is increased
resistance decreases
what are the main features of a series circuit
same current through each component
total p.d of power supply is shared between components
total resistance of all components is the sum of the resistance of each component
what are the main features of a parallel circuit
p.d across each branch is the same
total current through circuit is the sum of the currents in each branch - total resistance of the smallest individual resistor
