Question

Why does the connecting wires of electric heater not glow whereas it's coil glows?

Answer 1

this is because of different resistance the coil has higher resistivity than connecting wire so current flows more easily in wire . We can also look at ohms law which is V=IR and I : current and R : resistance are inversely proportional so as coil has higher resistance ( i.e why it glows red) and so less current flows through it and visa versa in wire.
thank you :)