F2 - SEM1 - Circuit - 8.6 Household electricity - Part B Flashcards

1
Q

What are the potential hazards in using electricity?

8.6 Household electricity

A

Overloading
Short circuits

8.6 Household electricity

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2
Q

How to avoid overloading?

8.6 Household electricity

A

Connect electrical appliances draw large current to different mains sockets

8.6 Household electricity

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3
Q

How does overloading occur?

8.6 Household electricity

A
  • too many electrical appliances are connected to a main socket
  • exceeds safety limit of a circuit

8.6 Household electricity

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4
Q

What happen when the number of branches increases?

8.6 Household electricity

A

The current flowing through the cell decreases

8.6 Household electricity

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5
Q

Fill in the blanks

Several appliances are connected to a single mains socket via ________

8.6 Household electricity

A

Several appliances are connected to a single mains socket via universal adaptor

8.6 Household electricity

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6
Q

Does the bulb light up? Why?

8.6 Household electricity

A

No
The connecting wire provides a path with a very low (nearly zero) resistance. The current is more likely to flow through the wire than the bulb. The bulb is short-circuited.

8.6 Household electricity

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7
Q

What happens to the nichrome wire?

8.6 Household electricity

A

The nichrome wire melt

8.6 Household electricity

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8
Q

Fill in the blanks

A short circuit provides a path with ________ for current to flow
A short circuit causes ________ to flow in a circuit

8.6 Household electricity

A

A short circuit provides a path with _a very low resistance_ for current to flow
A short circuit causes _a large current_ to flow in a circuit

8.6 Household electricity

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9
Q

What are the causes of short circuits in electrical appliances?

8.6 Household electricity

A
  • a loose or worn wire
  • dust and moisture on the circuit

8.6 Household electricity

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10
Q

How to avoid short circuits?

8.6 Household electricity

A

keep electrical appliances clean and dry

8.6 Household electricity

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11
Q

Why short circuit is dangerous and should be avoided?

8.6 Household electricity

A

Short circuit may overheat and damage an electrical appliance

8.6 Household electricity

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12
Q

What are the 3 safety designs to protect circuits?

8.6 Household electricity

A
  • Fuses
  • Circuit breakers
  • Earth wires

8.6 Household electricity

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13
Q

Draw the circuit symbol

Fuse

8.6 Household electricity

A

8.6 Household electricity

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14
Q

What is the purpose of fuse?

8.6 Household electricity

A

break a circuit when the current becomes too large
protects the circuit from the overheat current

8.6 Household electricity

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15
Q

What is a fuse made of?

8.6 Household electricity

A

A metal wire with a low melting point

8.6 Household electricity

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16
Q

What is the number printed on a fuse called? What does it mean?

8.6 Household electricity

A

fuse rating is the maximum current the fuse can stand

8.6 Household electricity

17
Q

What happens when the current is larger than the fuse rating?

8.6 Household electricity

A

The fuse will blow and cut off the current

8.6 Household electricity

18
Q

Fill in the blanks

A suitable fuse should having a rating ________ than the current passing through the electrical appliance when it is operating normally

8.6 Household electricity

A

A suitable fuse should having a rating _slightly higher than_ than the current passing through the electrical appliance when it is operating normally

8.6 Household electricity

19
Q

What should be done before replacing a blown fuse?

8.6 Household electricity

A

Fix the short circuit

8.6 Household electricity

20
Q

What happen to circuit breaker when a current exceeds the rating?

8.6 Household electricity

A

the circuit breaker turns to the OFF mode and cuts off the current

8.6 Household electricity

21
Q

How to reset circuit breaker?

8.6 Household electricity

A

switching the circuit breaker to ON mode

8.6 Household electricity

22
Q

What should you do if the circuit breaker keeps cutting off the circuit?

8.6 Household electricity

A

should ask a registered electrical worker to check the circuit

8.6 Household electricity

23
Q

What happen when the circuit becomes overloaded?

8.6 Household electricity

A
  • Electricity failure
  • a fire

8.6 Household electricity

24
Q

What is the purpose of Earth wire?

8.6 Household electricity

A
  • Earth wire connects the metal case of an electrical appliance to the ground
  • Protects us from electric shock

8.6 Household electricity

25
Q

What happen if you touch the metal case of an electrical appliance with a damaged Live wire touches the metal case?

8.6 Household electricity

A

You may be hurt or even killed by electric shock
A current from the live wire will pass through your body to the ground

8.6 Household electricity

26
Q

List 4 Should when using electricity

8.6 Household electricity

A
  • Use three-pin plugs with earth wire
  • Switch on an electrical appliance only after firmly plugging it into a socket outlet
  • Use** fuses with suitable fuse ratings**
  • Ask a registered electrical worker to immediately replace damaged cables, sockets and plugs

8.6 Household electricity

27
Q

List 4 Should Not when using electricity

8.6 Household electricity

A
  • Overload sockets
  • Cover electrical appliance at work
  • Let water seep into any electrical appliance
  • Touch sockets or switches with wet hands as this can result in electric shock

8.6 Household electricity