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### Course: Electrical engineering>Unit 9

Lesson 2: Hair dryer

# What is inside a hair dryer? (1 of 2)

In this video we explore ground fault interrupt circuits and how they keep us safe. Created by Karl Wendt.

## Want to join the conversation?

• What do solenoids do exactly?
• Solenoids most often act as electromagnets, meaning that when current passes through them a magnetic field around the coil is created. Transformers also use them to change the potential difference (voltage) through a conductor. In a transformer, current flows through a primary coil, which in turn induces a current in a secondary coil. If the secondary coil has more turns than the primary, the voltage is increased and if it has less turns it decreases the voltage. They are also used in radios to convert the radio waves into a flow of electrons (electricity).
• where did you find an 1875 hairdryer?
• I am pretty sure that you already know this but i am gonna answer this anyway,
the 1875 doesnt refer to the year it was manufactured in, it is a kinda product number, like the "5" in iphone 5.
(1 vote)
• At Brit said you need a professional to take apart the plug. Is Brit a professional?
• At , what is a linear solenoid?
• Linear just refers to the configuration of the solenoid. There are rotary-type solenoids as well that can act as switches, valves and other electromechanical devices. In the video, the solenoid is basically acting as a linear-actuated switch. If the internal circuitry of the dryer gets shorted because someone dropped it in their bath-tub, current is routed through the coils of the solenoid, which creates a magnetic field through the center of the coils (and the outside, but the center is the important part). This pushes the little metal spike out one end and breaks contact with the circuitry running to the actual hair dryer. Thus, the person can live to bathe and blow-dry another day. Preferably not at the same time.
(1 vote)
• Near why are PCB's green
(1 vote)
• PCBs can actually come in all sorts of colors; it just happens that the vast majority are green. The green stuff is actually a layer called solder mask, which makes soldering the board much easier. There are definitely other colors out there though: Arduino boards are blue, SparkFun boards are red, OSH Park boards are purple, Fritzing boards are white, etc.

Here's an explanation I found online: http://www.4pcb.com/pcb/
"The original masks used a base resin that was a 'brownish yellow' and a hardener that was a deeper muddy brown. When they were mixed together they created a honey brown color that apparently not very appetizing. They tried adding red pigments but it became a rusty adobe color and using blue simply made it a darker brown. None of them were very appealing colors. Since the laminate materials at the time had a green hue they tried adding more yellow and some blue and ended up with an acceptable green color. It became the standard color we are still using today."
• At he says hat you shouldn't open a plug without a professional, why not? what might happen?
(1 vote)
• I would say only worry about that if you plan to plug it back in. if certain parts are messed up inside the plug it can be a fire hazard, parts may explode, or it may ruin some of the wiring in your house. If you make sure it is unplugged and you won't be plugging it back in you wouldn't need a professional.
• do other plugs do the same thing because some plugs don't have 1 large side and 1 small size ?
(1 vote)
• It only depends on what kind of plug fits in. You don't need the one with the large and small, you could do with what you have as long as it fits in the right way.
• Are the same compartments found in this specific hair dryer found in any hair dryer?
(1 vote)
• what do you mean by the plug being able to sense difference enbetween