#### Transcript Electricity revision

```Electricity revision
What is the question?
Here are some answers what might the
question be?
Bistable latch
Diode-bridge
thermistor
NOT gate
direct current
P6 Content
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Resistors
Potential dividers
Motors
Generators
Transformers
Capacitors
Logic gates
Logic gates: key facts
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High or 1 usually 5V
Low or 0 usually 0V
NOT
AND
OR
NAND
NOR
Truth tables
OR Gate
AND Gate
Input 1 Input 2 output
Input 1 Input 2 output
0
0
0
?
0
0
?
0
1
0
0
?
1
0
?
1
0
1
0
?
0
1
?
1
1
1
1
?
1
1
?
1
NOT gate
Input
Output
1
0
0
1
Truth tables
NOR Gate
NAND Gate
Input 1 Input 2 output
output
Input 1 Input 2 output
0
0
?1
0
0
?
1
1
0
?1
1
0
?
0
0
1
?1
0
1
?
0
1
1
?0
1
1
?
0
Logic gates
Logic gates
0
0
0
1
Fan needs a large current, logic gates only supply a low current
The most complicated diagram you could be asked
Light a bulb when it is HOT and DARK and a swtich is turned on
Hot = 1
Thermister
First step?
Cold = 0
Second step?
Light = 1
LDR
Dark = 0
On/off
Switch
On = 1
off = 0
Last step?
The Bistable or Latch gate
SET
output
RESET
You are only ever expected to say how it works like this:
1. When SET becomes on the output switches ON……..
2. Even if SET becomes off the output stays ON
3. If the RESET becomes on the output becomes OFF
• more logic gate questions.rtf
Transformers
Transformers are used to _____ __ or step down
_______. They only work on AC because an ________
current in the primary coil causes a constantly alternating
_______ ______. This will “_____” an alternating
current in the secondary coil.
Words – alternating, magnetic field, induce, step up, voltage
Transformers
Transformers are used to step up or step down voltage.
They only work on AC because an alternating current in
the primary coil causes a constantly alternating magnetic
field . This will “induce” an alternating current in the
secondary coil.
Words – alternating, magnetic field, induce, step up, voltage
Transformer equation
You will need
to know this
one!
Vp
Vs

Np
NS
VP I P  VS I S
This helps
explain why
power is
transmitted at
high voltage
• P6 so far quiz.ppt
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