short note on ohmic and non ohmic substances with proper example

@kishor 
ohmic substances – these are purely conducter which obey ohms law at every temp , and pressure range . 
temp and pressure are kept as low and constant here . 
example – copper , tungsten . 
NON OHMIC SUBSTANCES – these are those substances which donot obey the ohms law in any condition . 
example – semiconducter and insulator , like diode, transister , etc .. 
HOPE IT CLEARS YOUR DOUBT 
ALL THE BEST ..