Resistor
Resistors are the most basic and common component. They're semiconductors, used to throttle current or reroute current in circuit. They are small, composed of powdered carbon (semiconductor), and coated in tan ceramic (insulator), with stiff wire (conductor) affixed to two electrodes. The four colored bands encode a value in Ohms: the first two bands represent digits, the third is a multiplier, the fourth is a margin of error. This brown-black-red-gold resistor is 1Kohm ± 5%. Brown is the 1, black is 0, red is 10^2— 1000ohms. Here's a handy calculator. Ohm's Law is the way to figure out what resistor you need in a given circuit: V=I*R, where V is voltage, I is amperage, R is resistance.
Photoresistor
Photoresistors are passive variable resistors. Their resistance is inversely proportional to the amount of light hitting them— more light means less resistance. To be used as a sensor, they require a voltage divider. Here's a great tutorial.
Potentiometer
Potentiometers are active variable resistors. As you turn the knob of a potentiometer, current passes through a varying amount of semiconductive material. At one end of the range the pot is very conductive, at the other it's very resistive. Here's the basic Arduino circuit.
Diode
Diodes are used to inhibit the flow of electricity in one direction. They're commonly used in DC motor circuits to prevent current generated by the motor from flowing back into the circuit. Here's a video about the diode from Make magazine.
Light Emitting Diode
LEDs are diodes that emit some of the energy passing through them as photons. They are very energy efficient: don't get hot, last a long time, and don't consume much power. They're useful as cheap indicators, to monitor functionality in a circuit. Here's the Arduino Blink tutorial.
Resistors are the most basic and common component. They're semiconductors, used to throttle current or reroute current in circuit. They are small, composed of powdered carbon (semiconductor), and coated in tan ceramic (insulator), with stiff wire (conductor) affixed to two electrodes. The four colored bands encode a value in Ohms: the first two bands represent digits, the third is a multiplier, the fourth is a margin of error. This brown-black-red-gold resistor is 1Kohm ± 5%. Brown is the 1, black is 0, red is 10^2— 1000ohms. Here's a handy calculator. Ohm's Law is the way to figure out what resistor you need in a given circuit: V=I*R, where V is voltage, I is amperage, R is resistance.
Photoresistor
Photoresistors are passive variable resistors. Their resistance is inversely proportional to the amount of light hitting them— more light means less resistance. To be used as a sensor, they require a voltage divider. Here's a great tutorial.
Potentiometer
Potentiometers are active variable resistors. As you turn the knob of a potentiometer, current passes through a varying amount of semiconductive material. At one end of the range the pot is very conductive, at the other it's very resistive. Here's the basic Arduino circuit.
Diode
Diodes are used to inhibit the flow of electricity in one direction. They're commonly used in DC motor circuits to prevent current generated by the motor from flowing back into the circuit. Here's a video about the diode from Make magazine.
Light Emitting Diode
LEDs are diodes that emit some of the energy passing through them as photons. They are very energy efficient: don't get hot, last a long time, and don't consume much power. They're useful as cheap indicators, to monitor functionality in a circuit. Here's the Arduino Blink tutorial.
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