electricity Flashcards
electric current?
S.I unit?
- rate at which electric charges flow
- Ampere (A)
how to measure electric current
- ammeter (series)
- positive terminal of ammeter connected to positive of source of energy
conventional flow
flow of positive charges from positive to negative terminal
electron flow
- movement of electron in conducting wires
- negative to positive terminal
potential difference
- the amount of energy needed to drive an electric charge across two points
S.I unit for potential diff
volt
1 V = 1 joule of energy needed
voltmeter
- measure potential diff
- parallel
- positive to positive
- opposite bulb
resistance
- opposition flow of electric current
- fixed / variable resistors
- Ohm (SI unit)
resistance formula
P. d (v) / current (A)
factors affecting resistance
length - longer the wire, the greater the resistance
thickness - the thinner the wire, the greater the resistance
fix resistor vs variable resistor
FIX - resistance value is fix
- cant vary amt of current
VARIABLE - resistance value varies
- vary amt of current
resistors in series
- if ammeter reading decrease, bulb becomes less bright
- decrease in current means resistance INCREASE
- thus, adding a resistor in series INCREASE overall resistance
resistor in parallel
- ammeter reading increases
- bulb becomes brighter
- overall resistace decrease
variable resistor
- rheostat
- slider to left - resistance decrease
- slider to right - resistance increase
resistance + heat
- the greater the resistance, the greater the amt of heat produced
power?
S.I unit?
- the conversion of electrical energy into other forms of energy in 1 sec
- Watt (W)
formula of power
energy (J) / time (sec)
calculating household energy consumption
Energy used = power (kW) X time (h)
cost = energy used (kWh) X unit cost
fuse
- when fuse exceeds normal amt, the metallic wire inside melts
- open circuit
rating of fuse
determines the amt of current flowing through
