What is it??


Identify and define

Thermostats		A thermostat is a device for regulating the temperature of a system so that the system's temperature is maintained near a desired setpoint temperature. The thermostat does this by controlling the flow of heat energy into or out of the system. Plain English: A thermostat will open and break the circuit once the set temperature is reached and reset itself once it cools down.



Thermistors		A thermistor is a type of resistor with resistance varying according to its temperature. The word is a combination of thermal and resistor. Thermistors are widely used as inrush current limiters, temperature sensors, self resetting over current protectors, and self regulating heating elements. If $k$ is negative, the resistance decreases with increasing temperature, and the device is called a negative temperature coefficient (NTC) thermistor. Plain English: A thermistor is usually used to control a charger. As the temperature increases it will either slow or shut off the charger.



Thermal cutoff		A thermal fuse is a cutoff which uses a one-time fusible link. Unlike the thermostat which automatically resets itself when the temperature drops, the thermal fuse is more like an electrical fuse: a single-use device that cannot be reset and must be replaced when it fails or is triggered. One mechanism is a small meltable pellet that holds down a spring. When the pellet melts, the spring is released, separating the contacts and breaking the circuit. Plain English: A thermal cutoff will open and break the circuit once the set temperature is reached. It will not reset itself.


Polyswitch		A polymeric positive temperature coefficient device (PPTC) is a passive electronic component. Commonly called "resettable fuses", they are used to protect against over current faults in electronic circuits . They are actually non-linear thermistors, however, and cycle back to a conductive state after the current is removed, acting more like circuit breakers. Plain English: A Polyswitch will open and break the circuit once set current level is reached. A polyswitch will reset itself.


Resistor		A resistor is a two-terminal electrical or electronic component that opposes an electric current by producing a voltage drop between its terminals in accordance with Ohm's law: $V = I \cdot R$ The electric current is equal to the voltage drop across the resistor divided by the current through the resistor while the temperature remains the same. Plain English: A resistor is usually used to limit the current of a device.


Diode		The directionality of current flow most diodes exhibit is sometimes generically called the rectifying property. The most common function of a diode is to allow an electric current to pass in one direction (called the forward biased condition) and to block it in the opposite direction (the reverse biased condition). Thus, the diode can be thought of as an electronic version of a check valve. Plain English: A diode only allows current to flow one way.


Fuse		In electronics a fuse (short for fusible link), is a type of over current protection device. Its essential component is a metal wire or strip that melts when too much current flows, which breaks the circuit in which it is connected, thus protecting the circuit's other components from damage due to excessive current. Plain English: A fuse will open and break the circuit once the set current is reached. It will not reset itself.


Ferrites		A ferrite bead is a passive electric component used to suppress high frequency noise in electronic circuits. Ferrite beads employ the mechanism of high dissipation of high frequency currents in a ferrite to build high frequency noise suppression devices. Ferrite beads may also be called ferrite cores, ferrite rings, ferrite EMI filters, or mistakenly as ferrous beads. Plain English: A ferrite will filter out high frequency interference and electrical noise.