resistor is a cylindrical shape non-polarized component whose two
terminals are identical.
Standard symbol of resistance:
Each resistor is characterized by a physical quantity called resistance
is denoted by R and its unit is the ohm of symbol:
For a resistor with a value of 400 ohms we may note its value
R = 400 Ω
Resistance not only characterizes the resistors but also other
electrical components and conducting materials.