Transcript Electronics

Electronics
A light dependent resistor
A light dependent resistor can resist the flow of
electricity through it
Set up the circuit:
Lamp distance from LDR
What happens to the
light bulb, how bright
is it?
5cm
10cm
What is your conclusion about how the LDR
works??
Light Dependent resistor
• The amount of resistance it
has depends on how much
light is shining on the
resistor.
• The more light is shining on
the LDR the more current it
lets flow through it
Application of an LDR
• LDRs are used as controls of street lamps
Electrical switches
• A Switch can be used to complete or
break a circuit
A diode
• A diode allows electrical current to flow in
one direction only.
Investigating a diode in a circuit
Which of these circuits will the bulb light up in?
What way should the diode be facing for electricity
to flow?
Diode
• When connected to a power
supply it will only allow
electricity to flow if it is forward
facing
Applications of a diode in a circuit
•Diodes are used to change alternating current to direct
current in a circuit
In an a.c power supply the electricity is
constantly changing direction of flow!
The diode will only allow the electricity to flow
when it flowing in one particular direction!
LED
• An LED is a diode that emits light as
current passed through them.
Symbol
LEDS
• LED’s are often used as power indicators
on radios, TV’s and other electronic
devices.
• LED’s are used instead of bulbs as they
need less current to work!!