A resistor's resistance is measured in ohms. The higher the resistance the less current will flow with a constant voltage applied across the resistor. In terms of Ohm's Law Voltage = Current x Resistance.
That completely depends on the task that you want the resistor to perform, and on where the 20 volts appears in the circuit.
A "pull-up" resistor is a resistor used to to perform a specific electronic function - it is not a different type of resistor. A very small current flows through a pull-up resistor so it does not need to be high wattage (1/8 watt is generally fine). The value of a pull-up resistor depends on the resistance of the sensor. If it is simply on or off (no resistance) then a typical pull-up resistor might be 10k ohms.
A passive device is a diode resistor coil and so forth it perform no enhancement to the circuit or act on it.
A: RATING is a term to describe the capabilities of any components active or passive to perform as designed. Power of a resistor must be rated to safely dissipate within its own power rating
That completely depends on the voltage of the battery.The energy delivered by the battery and dissipated by the resistor in one minute will be[ 60 x (Voltage of the battery)2 / 21 ] joules
yes, a variable resistor
Adding more components changes how a resistor works. In a series circuit, resistance goes up, slowing current. In a parallel circuit, resistance drops, letting more current flow. The effect depends on how the components are connected.
First you need to know the value of the resistor. Follow the link for a handy resistor calculator After determining the value of your resistor simply test the resistor with an ohmmeter to see if it is at true value. General use should be within + or - 5%
Otis F. Boykin invented the wire precision resistor and the electrical resistor.
A non-ohmic resistor doesn't have a constant resistance. A ohmic resistor has a constant resistance.
Resistor value is defined by the Resistance the resistor offers in Kilo ohms/ohms value given by color codes on the resistor.
A cement resistor is typically used as a power resistor (a resistor whose power rating is greater than 1 W).