electricity Flashcards
step up transformer
INCREASES voltage
reduces current
step down transformer
DECREASE volltage
increases current
what is current
flow of electrical charge
Amperes
A
what is potential difference
energy transfer per unit of charge
Voltage
V
what is a battery
2 or mor cells
what is elecrical charge
quantity of electrons/charge that psses a ifixed point per seond
Coulombs
C
series vs parallel
- current
- potential difference
- total resistance
- S- current same across all components
- P- current splits between branches
- S- potential difference shared between all components
- P- potential difference same across all components
- S- total resisanace= sum of all resistance
- P- total resistance decreases and less than resistance in any of the components
if the cells in a battery are drawn ina circuit fac each other what is the volatge
what about if 3 cells- 2 right way, one wrong way?
- 0v
- wrong one cancles one of the volts out but keeps the other one
what is the flow of current from
and what is it often drawn as
negative to positive- elecrons
conventional current- drawn opposite
what does Ohm’s law?
The current through a conductor is directly proportional to the potential difference across it
ONLY at constant temperature
called ohmic conductors
ohmic conductors examples
- fixed resistors
- wires
- heating elements
filament lamp
iv graph
- not ohmic conductor
- current not directly proportional to potential difference
- resistance of lamp increases as temperature inceases
why does the resistnace increase in a filament bulb?
- as current increases so does temperature
- temperature causes increase in kinetuc energy in metal filament, viberating
- this creates resitstance as it is dufficult for current- free electosn o pass through
diodie
iv graph
- diode only goes one direction
- when opposite direction- resistancee is very high
LDR
- light dependent resistor
- increse in light decrease in resitance
- used in garden lamps
thermistpr
- increase in tep decrease in resistance
- used in thermostats
what energy stores is energy transferred to in pplicances
just 2
give examples
and both
- kinetic- fan
- thermal- kettle
- both- hairdryer
what has more power
thermal energy stores or kinetic
thermal
direct current
1 direction
produced by cells and batteries
alternating current
constantly changing current direction
produced by generators like mains
mains electricity
a.c
50Hz
230V
brown wire
blue wire
green & yellow wire
brown- live- 230V- fuse in plug
blue- neutral- 0V- completes circuit
green & yellow- earth- safety
