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Properties of circuits

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In a circuit there are electrical components . This is a device such in an

electric circuit such as: a battery, a switch or lamp etc.These connect

together in two ways: series or in parallel.


Series connections

When batteries, cells and lights are connected in a sequenceit is called a series.

The same value of current, this is a moving electrical charge which flows

through each component,connected in a series.


Two lamps connected in series

The circuit illustrates a circuit with two lamps connected in series. If one of

the lamp breakdowns, the other lamp will not light because it is in a series.

Here we have, two lamps connected in series with an open switch and a cell:



Series circuits are helpful to identify when one of the components has

broken-down. For example, a fuse, which is a device which controls the

overload of the current to keep it safe, must be connected in series in

order for it to work. If Christmas tree lights all go out when one bulb

breaks, they are connected in series.


The sum of all the potential differences across the components in a series

circuit is equal to the total potential difference across the power supply.


Parallel connections

Parallel connections are when components such as lights that are connected

on separate loops.Here, the current is divided between each component

connected in parallel.If one lamp breaks, the other lamp will still light.



Two lamps connected in parallel with an open switch and a cell

In our homes, the lights are connected in parallel and ensures each bulb

receives the full voltage. If one bulb breaks the others remain on.

In a parallel circuit the current supply of electricity is more than the current in

each branch. Note, ehe sum of all the current in every of the branches

equals to the current from the electrical supply.


Electricity Supply  =  branch 1 + branch  2 + branch 3


C electricity

Alternating current

If the current constantly changes direction it is called alternating current, or

AC. Mains electricity is an AC supply. The UK mains supply is about 230 V.

It has a frequency of 50 Hz, which means that it changes direction and back

again 50 times a second. The diagram shows an oscilloscope screen

displaying the signal from an AC supply.


Oscilloscope trace illustrating alternating current


DC electricity

Direct current

DC is when a current flows in only one direction. Examples of DC electricity

are batteries and solar cells supply DC electricity. A battery typically supplies

1.5 V. The illustration shows an oscilloscope screen. It is displaying the

signal from a DC supply.