chapter 13 Flashcards
purpose of cell
energy source to rive electricity in the circuit
electric charge
carried by negatively charged electrons that move within the connecting wires
wires
allow electric charge to flow through the components
electrical device
energy is transferred from the cell to the device
electric current
rate at which electric charge flows
what causes electric current
movement of electrons in the electrical conductors
ammeter
measure current flowing through circuit, ampere (A)
how is ammeter connected
series
- - to - of cell
- + tp + of cell
potential difference: voltage
amount of energy needed to move a unit charge from one point in a circuit to another
how to measure pd/voltage
voltmeter:
volt (V)
how to connect voltmeter
parallel
- negative to negative
- positive to positive
electrical resistance,R
measure of how much eh component opposes the flow of electric current
electric insulator
reisistance is so high that current cannot flow through it
electric conductor
low resistance
SI unit of electrical resistance
ohm Ω
electrical conductors with low resistance
copper silver
electrical conductors with higher resistance
tungsten nichrome
- convert electrical energy to other form of energy (light bulb light->heat)
types of resistors
- variable
- non-variable
variable resistor
range of electrical resistance that can be adjusted
non-variable resistor
fixed, non-adjustable electrical resistance
what happens when 2 resistors are added in series
- reading on a meter decreases
- bulb is less bright
- decrease in current flowing through circuit, but overall resistance has increased
variable resistor application
household appliances to control current in a circuit
- control dimness/brightness of light
- convert electrical energy to light/heat energy
what happens when 2 resistors are added in
- there is more than one path fro current to flow
- ammeter reading increases, bulb becomes brighter
- increase in current flowing through ciruit -> resistance decreased
useful effects of electricity
chemical effect
heating effect
chemical effect of electric current
when electric current in passed through certain chemical solutions/liquids, chemical change take place
coating for medical instruments
- repeated cleaning will increase rate of corrosion
- electroplating these instrument with a layer of protective metal can minimise damage and lengthen their lifespan
- can destroy harmful microorganisms
coating for implants
- electroplated
- metal can cause allergic reactions and are more likely rejected by the body
- coating metal with living tissue can reduce infection and rejection
heating effect for electric current
- some electric current converts to heat energy
- wire made of a high resistance material, that can withstand high temperatures
magnetic effect of an electric current
- when no current, the needle points to north
- when current flows, the needle deflects from the position
electro magenet
- increase: insert iron core inside the coil fo wire
harmful effects of electricity
electrical fire
electric shock
electric fire
electric circuit is damaged, or multiple plugs are inserted into the same socket
- a very large amount of current has to be drawn from the power supply
- excessive heat, cause wires to melt and fire
electric shock
wires carrying electricity to electrical appliances are insulated with plastic/rubber
- protects used from electric chock
- when insulating material is worn out, wires are exposed, posing as a potential hazard
- water is an electrical conductor which allows current to flow through it
safety devices
fuse
-circuit breaker
fuse
fuse metal when excessive current higher than the fuse rating flows through it
- maximum amount of current that can flow through fuse before the wire inside melts
1kw is
100w
circuit breaker
- when current flow is too large, switch linked to appliance trips and cuts off current, preventing electric chocks
