electricity Flashcards
what are the differences between series and parallel circuits in regard to current and voltage?
series
- the same current flows through all the components
- the potential difference across the components isn’t the same, the total potential difference is equal to the sum of potential differences across each component
parallel
- the current flowing in a junction is equal to the current leaving it, the sum of the currents in each section is equal to the total current
- the potential difference across each branch is the same
voltage is also known as ……….
potential difference
where must a voltmeter be placed in a circuit?
in parallel with the component that is being measured
unit for volts
Joule per coulomb
what is current
the rate of flow of charge
what is an ammeter and where must it be connected in a circuit?
it measures current and should be placed in series with the component it is required to measure
measured in Amps
in a closed circuit, if there is a potential difference in the circuit there will also be a ………..
current
how does changing the resistance in a circuit change the current?
- current is inversely proportional to resistance, therefore at a constant voltage, increasing the resistance will decrease the current
- in an electric circuit the flow of electrons causes a current. A high resistance makes it harder for electrons to pass through and therefore reduces the current
how do diodes work?
allows current to flow in one direction. if current is flowing the right way, the resistance very large and small voltages
bu then at higher voltages the resistance becomes very small
when an electric current flows through a resistor why does it heat up?
there are collisions between the electrons and the ions in the resistor’s lattice.
This causes a transfer of kinetic energy into thermal energy, which is released into the surroundings
what is the unit for energy transferred per second?
Power in Watts
what is meant by direct current?
what is meant by alternating current?
current flows only in one direction
direction of current changes continuously as time passes
what type of current do batteries and cells supply?
direct current
how do objects become negatively charged?
how do objects become positively charged?
- electrons are transferred to the rod by friction
- as the rod gains electrons it becomes negatively charged
- friction removes electrons from the rod
- as the rod looses electrons it becomes positively charged
a) how do opposite charges behave?
b) how do like charges behave
a) opposites attract
b) like charges repel
how does a fuse wire stop the device from getting damaged?
when the current becomes too high the fuse wire will melt and break
therefore stopping current from flowing to the appliance and preventing damage
measurement for charge, Q
Coulombs (C)
measurement for voltage, V
volts (v
resistance, R is….
something that slows down the flow of charge
measurement for resistance
ohms (Ω)
Double insulation
wires insulated, outer case insulated too
How do circuit breakers work?
a reusable fuse
An electromagnet switch opens above a set current, breaking the circuit
Advantages of circuit breaker
- More sensitive; detect currents that are just above the current taken by an appliance
- Can be reset once the circuit is broken
Why does the temperature increase when current flows through a resistor?
- Metal atoms have loose electrons on their outer shells. These form a sea of delocalised electrons around the tightly packed metal ions
- Electrons flow through the metal and collide with the atoms
- These collisions transfer energy in the form of heat
