Basic nature of electric current/voltage
An often used model to explain electricity and electric current is the water model. Voltage then becomes water pressure (which agrees with water column level), and current becomes water flow through pipes. The thinner the pipe diameter the higher the resistance and the less current will flow.  

If you talk about lighting, do you mean incandescent lighting? That is caused by the heating up of a filament because of the power generated in its resistance. The temperature becomes so high that the filament glows white hot. At lower currents you will have an orange/red glow.