13 Electrical Systems Flashcards by Chun Min Teo

What is this symbol?

cell

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What is this symbol?

battery

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What is this symbol?

open switch

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What is this symbol?

closed switch

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What is this symbol?

bulb

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What is this symbol?

fixed resistor

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What is this symbol?

variable resistor

aka rheostat

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What is this symbol?

ammeter

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What is this symbol?

voltmeter

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What are the 4 main components of an electrical system?

Think about what is needed

1) cell
2) electric charge
3) connecting wires
4) electrical device or load

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What is an electric current, I?

The rate of flow of electric charges.

rate of flow simply means how many per unit time.

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What is the SI unit of current?

ampere (A)

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How should an ammeter be connected in a circuit?

in series with the component

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What is potential difference?

The amount of energy needed to move a unit charge from one point of the circuit to another.

another word for potential difference is voltage

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What is the SI unit of potential difference?

volt (V)

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How should a voltmeter be connected in a circuit?

parallel to the component

What is the purpose of a resistor?

to reduce the flow of current in a circuit

What is electrical resistance?

A measure of how much an electrical component opposes the flow of electric current.

What is the SI unit of electrical resistance?

ohm (Ω)

Name 2 high-resistance metals.

1) nichrome
2) tungsten

Name 3 effects caused by electric current.

1) magnetic effect
2) chemical effect
3) heating effect

What is the chemical effect of electric current use for?

1) electroplating
2) extraction of metals

What is the heating effect of an electric current use for?

heating element of electric appliances such as hair dryer etc.

What is the high-resistance metal used in the heating element of an electrical appliance?

nichrome

What is the magnetic effect of an electric current use for?

electromagnet ## Footnote the electromagnet is then used in a wide variety of applications such as robots and MRI.

State 2 harmful effects of electricity. ## Footnote They are also known as electrical hazards.

1) electric fire 2) electric shock

Describe how an electric fire occur.

When multiple plugs are inserted into the same socket, overloading occurs. This causes a large current to flow through the wire causing the wires to generate excessive heat which causes the wires to catch fire.

Describe how an electric shock occur.

When we use electrical appliances in wet places, electric current may flow through our body giving us an electric shock. ## Footnote Other ways that causes electric shock are 1) inserting fingers into power sockets, 2) touching the exposed wires with damaged insulation

What are the 2 safety devices used in a household electric system?

1) fuse 2) circuit breaker

Briefly describe how a fuse works.

A fuse has a fuse rating which states the maximum allowed current before it breaks. When the current exceeding the rating flows through the fuse, the fuse will melt and break the circuit.

Briefly describe how a circuit breaker works.

When a faulty appliance causes the current flowing through the circuit breaker to be too large, the switch in the circuit breaker trips and disconnect the circuit.

What is *power* of an electrical appliance?

The amount of electrical energy converted to non-electrical energy per unit time.

What is the SI unit of power?

watt (W)

How can we conserve electricity at home?

1) use appliances with energy labels with 3 or more ticks 2) use the fan instead of air conditioning 3) switch off water heater after use 4) switch off power socket to reduce standby power ## Footnote These are just some examples.