Resistor

Resistor is a passive two terminal electric components that implements electrical resistance as a circuit element. The current through a resistor is represent by ohm's law; V=IR

Resistor has a color code on it with each color representing a number between 0 to 9. You can learn to understand the value of a resistor by reading the color.

The simplest way is by measure the value at your resister using multimeter. Set it to Ohm and start measure on each side of the resistor.

Typical value you will see in a tube amplifier circuit is

100K = 100 x 1000 = 100000 ohm

100R = 100 ohm

1K8 = 1.8 x 1000 = 1800 ohm

1M2 = 1.2 x 1000000 = 1200000 ohm

Resistor come on difference wattages. We usually use 1/2W, 1W, 2W, 5W, 10W. Even thought it can with stand 10W, it does not mean it won't be hot.