Research Check 14

- Resistance in electronics is a lot like friction in mechanical systems; it puts a stop on electrons as they move through materials.
- resistors are components that control amounts of resistance for electronic circuits.
- resistance is a measure of an object's opposition to the flow of electrons.
- resistance makes it possible to generate heat and light, restrict the flow of electric current, and ensures that the correct voltage is supplied to the device.
- resistance depends on several factors like material, cross-sectional area,length, and temperature.
- "R" is used to represent resistance in an electronic circuit.
- resistance is measured in ohms.
- kilohms is thousands of ohms and megohms is millions of ohms.
- LEDs eat up current and drain as much as they can, but can burn themselves out if they draw too much current and a resistor limits the amount of current sent to the LED.
- resistors also protect sensitive components such as a transistor.
- resistors come in two basic functions, fixed and variable.
- a fixed resistor supplies a constant, factory determined resistance.
- the actual resistance of a fixed resistor may vary up or down.(ex: a 1,000 ohm resistor with a 5% tolerance could range from 950-1050 ohms)
- high precision resistors come within a 1% of their nominal value.
- standard precision resistors can vary from 2% to 20% of their nominal values.
- a variable resistor also known as a potentiometer allows you to continually adjust the resistance from zero ohms to factory determined maximum value.