Download S.2 Chap 8.6-7 Fuse, three pins, overload and short circuit V1

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Transcript
STCC
S.2 I.S. Chap 8.6-7 Fuse, three pins, overload and short circuit
Self-reflection Exercise
Learning targets :
1. I can tell what happens when current pass through a conductor. (Textbook p.120 )
2. I can tell how fuse protect us and know how to choose a suitable fuse.(Textbook p. 123)
3. I can tell the colours and connections of live wire, neutral wire and earth wire. (Textbook p.125, 128, 130)
4. I can tell what happens when overload occurs and short circuit occurs. (Textbook p.133, 135)
Q1 (Learning target 1, Level 1)
When a current passes through a conductor, the temperature of the conductor _______________.
Some __________________ energy is changed to ______________ energy.
(I am sure I get it !! / I am not sure ?! / I totally have no idea ??)
Q2 (Learning target 2, Level 1) Draw the circuit symbol for a fuse
(I am sure I get it !! / I am not sure ?! / I totally have no idea ??)
Q3 (Learning target 2, Level 1)
If the current passing through the fuse is _____________ than the fuse rating, the fuse will _________ and
The current will be ________________ to prevent the circuit from __________________ .
(I am sure I get it !! / I am not sure ?! / I totally have no idea ??)
Q4 (Learning target 2, Level 1)
If the operating current of a computer is 3.5 A, which of the follow fuse is suitable for the computer?
2A
5A
10 A
13 A
(I am sure I get it !! / I am not sure ?! / I totally have no idea ??)
Q5 (Learning target 3, Level 1)
The fuse should be connected to
live wire
/
neutral wire
/
earth wire.
(I am sure I get it !! / I am not sure ?! / I totally have no idea ??)
Q6 (Learning target 3, Level 2) What are the pins X, Y, Z below?
(I am sure I get it !! / I am not sure ?! / I totally have no idea ??)
1
Q7 (Learning target 3, Level 2) What are the holes X, Y, Z below?
(I am sure I get it !! / I am not sure ?! / I totally have no idea ??)
Q8 (Learning target 3, Level 1) What is the colours of the wires in a three-pin plug?
Live wire :
Neutral wire :
Earth wire :
(I am sure I get it !! / I am not sure ?! / I totally have no idea ??)
Q9 (Learning target 3, Level 1) About earth wire :
_____________________ of appliances should be connected to the earth through the _________________
to protect users from getting _____________________________.
(I am sure I get it !! / I am not sure ?! / I totally have no idea
Q10 (Learning target 4, Level 1)
Overload occurs when _______________________________ are connected to a single mains socket.
This is dangerous due to the _____________________________ of current.
(I am sure I get it !! / I am not sure ?! / I totally have no idea ??)
Q11 (Learning target 4, Level 2)
When the switch is open :
light bulb
lights up /
does not lights up
When the switch is closed : light bulb
lights up /
does not lights up
(I am sure I get it !! / I am not sure ?! / I totally have no idea ??)
2
Q12 (Learning target 3, Level 3)
X : ________________
Y : ________________
Z : ________________
(I am sure I get it !! / I am not sure ?! / I totally have no idea ??)
Q13 (Learning target 3, Level 5)
Why do most electric appliance use 3-pin plugs instead of 2-pin plugs? (2 marks)
_________________________________________________________________________________________
_________________________________________________________________________________________
(I am sure I get it !! / I am not sure ?! / I totally have no idea ??)
Q14 (Learning target 3, Level 1)
The mains voltage in Hong Kong is _________________
(I am sure I get it !! / I am not sure ?! / I totally have no idea ??)
Q15 (Learning target 2, Level 1)
State the function of the fuse.
In case of overloading or electricity leakage, the fuse _______________ and _______________ the electric
circuit in order to prevent _______________ of the circuit.
(I am sure I get it !! / I am not sure ?! / I totally have no idea ??)
Q16 (Learning target 3, Level 1) Write down the function of the device shown.
It is a ___________________________________ .
It _____________________________
if the current passing through the circuit is above its rated value.
(I am sure I get it !! / I am not sure ?! / I totally have no idea ??)
3
Self-checking ANSWERS
Q1 When a current passes through a conductor, the temperature of the conductor increases.
Some electrical energy is changed to heat energy.
or
Q2
Q3 If the current passing through the fuse is greater than the fuse rating, the fuse will blow and
The current will be cut off to prevent the circuit from overheating .
Q4 If the operating current of a computer is 3.5 A, which of the follow fuse is suitable for the computer? 5 A
Q5 The fuse should be connected to live wire.
Q6 X : Earth
Y : Live
Z : neutral
Q7 X : Earth
Y : neutral
Z : Live
Q8 Live wire : Brown
Neutral wire : Blue
Earth wire : Green and yellow
Q9 Metal cases of appliances should be connected to the earth through the earth wire
to protect users from getting electric shocks.
Q10 Overload occurs when too many appliances are connected to a single mains socket.
This is dangerous due to the heating effect of current.
Q11 When the switch is open :
light bulb lights up
When the switch is closed : light bulb does not lights up (short circuit occurs)
Q12
X : Earth
Q13
To make sure that the earth wire connects to the metal case of the appliance
and protect users from an electric shock.
Q14
The mains voltage in Hong Kong is 220 V
Q15
In case of overloading or electricity leakage, the fuse melts and breaks / cut off the electric circuit in
order to prevent overheating of the circuit.
It is a circuit breaker .
It breaks the circuit / switches off if the current passing through the circuit is above its rated value.
Q16
Y : Live
Z : Neutral
4