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Dissecting a Hair Dryer

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Anthony Carrozzi

on 26 May 2014

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Transcript of Dissecting a Hair Dryer

Dissecting a Hair Dryer
Description of the Hair Dryer
What is a hair dryer?
Hair dryers are hand-held, electromechanical devices used to dry and style hair.
What does it look like?

Hair Dryers look like gun-shaped plastic shells, weighing about 1lb (453.59g) and measuring approximately 12 x 4 x 9 inches (30 x 10 x 23 cm).

Components of a Circuit
The components of a circuit that I identified in the hair dryer were the:
Power Supply
Connecting Wires
Thermal Fuse

Dissecting the Hair Dryer
How do you dissect a hair dryer?
The following steps show what I did when taking apart my hair dryer.

Video: What is Inside of a Hair Dryer?
Description of the Hair Dryer
What is a hairdryer?
What does it look like?
How does it dry hair?
How does it blow hot air?
Electrical Information

Topics to Discuss
Components of a Circuit
What components of a circuit are found inside a hair dryer?

Dissecting the Hair Dryer
How do you take apart a hair dryer?

How does it dry hair?
In order for this device to dry hair it must:
Accelerate the evaporation of water.
Blows hot air to heat the air surrounding each strand of hair.
More water than usual can now move from the hair to the surrounding air.
Since warm air is able to contain more moisture than room temperature air.
The increased temperature also makes the individual water molecules lose their attraction.
This forces the water to turn from a liquid to a gas.
How does it blow hot air?
The process in which hair dryers emit hot air is quite simple:
Once the device is turned "on" current flows through the circuit.
This powers the heating element and the small electric motor.
The motor starts to spin itself and the fan that it is attached to.
The airflow generated by the fan is sent down the barrel of the dryer.
The heating element warms the air by forced convection.
Finally, the hot air streams out of the nozzle, onto the users hair.
Electrical Information
Electrical Current (I)
A measure of the rate of electron flow past a given point in a circuit; measured in amperes (A).
The maximum current of my hair dryer is 16 A and the minimum current is 8 A.

Electrical Power [Wattage]
The rate at which electrical energy is being used or produced; measured in watts (W).
The wattage of my hair dryer is 1875 W.

Potential Difference [Voltage] (

The difference in electric potential energy per unit charge measured at two different points; measured in volts (V). The maximum voltage of my hair dryer is 250 V and the minimum voltage is 125 V.
Power Supply
What is the Power Supply?
A device that provides power to electric devices.
What supplied the hair dryer with power?
Wall outlets
Since the electricity that comes from wall outlets originates from an electrical generating station, it is called alternating current (AC) [a flow of electrons that alternates in direction in an electric circuit].
This means that a hair dryer uses AC power (except the motor which moves the fan).
Connecting Wires
What are Connecting Wires?
Wires used to connect the different electrical components of the circuit.
Where can the connecting wires be found in the dryer?
The external wire which comes from the device is called the power cord.
It is made of copper and insulated by thermoplastic.
This cord carries electricity from the outlet to the device.
The internal wires take the electricity from the power cord and deliver it to all of the parts of the circuit.
They are also made out of copper and insulated by plastic.
What is a Switch?
A device in an electric circuit that controls the flow of electrons by opening (or closing) the circuit.
What switches are found in the hair dryer?
There are three switches inside the hair dryer: the "on/off" switch, the "temperature" switch, and the "rate of airflow" switch.
The electricity from the connecting wires travels through these switches to let them perform their specific function.
The "on/off" switch simply completes the circuit when it is set "on" and breaks the circuit when it is set "off."
The "temperature" switch varies the amount of electrical current that gets to the heating element whether temperature is set on either "low" or "high."
The "rate of airflow" switch varies the amount of current given to the fan's motor whether the speed is set on "low" or "high."
What is a Load?
The part of an electric circuit that converts electrical energy into other forms of energy.
What are the loads found in the hair dryer?
There are two loads inside the hair dryer: the motor and the heating element.
They are powered by the electricity delivered by the connecting wires.
The motor converts electrical energy into mechanical energy to turn the fan.
The heating element converts electrical energy into thermal energy to warm the air being emitted from the hair dryer.
What is a Resistor?
A device that reduces the flow of electric current.
What resistors are found in the hair dryer?
The only resistor found in the hair dryer is the heating element.
Although it is a load, it also acts as a resistor.
The motor in the hair dryer can only run on 12 V.
For this reason, the heating element brings the current down and consequently lowers the voltage so that the motor is able to operate.
Thermal Fuse
What is a Thermal Fuse?
An electrical safety device that interrupts electric current when heated to a specific temperature.
Why is there a thermal fuse in the hair dryer?
If temperatures within the hair dryer get too high, the thermal fuse will blow and shut down the machine.
This prevents the housing from melting and limts potential harm to the user.
The thermal fuse is attached to the heating element and lies just under the rows of nichrome wires.
What is a Diode?
An electronic device that restricts current flow chiefly to one direction.
Why does a hair dryer need diodes?
Since every part of the hair dryer runs on AC power but the motor does not, diodes are used to convert this alternating current into direct current (DC) [ a flow of electrons in one direction through the circuit] in order to turn the fan.
Step #1
Find an old hair dryer that does not work anymore
Step #2
Use a Philips head screwdriver to remove the plastic housing
Step #3
Set the plastic housing aside
Step #4
Examine the major components of a circuit I previously discussed
Motor (inside of fan)
Connecting Wires
Heating Element
Step #5
Examine the less noticeable components of a circuit I previously discussed
Thermal Fuse
By Anthony Carrozzi
Nelson Perspectives 9 - Textbook
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