AI-generated practice question — model-generated for extra practice, not a previous-year CBSE board question.
(A) Both A and R are true and R is the correct explanation of A.
The heating element (made of alloy like nichrome) has much higher resistance than the copper cord, so it dissipates more heat ($H = I^2Rt$) and glows.
The key concept is Joule's heating: $H = I^2Rt$. Since the same current flows through both cord and element (series), heat produced depends directly on resistance. The nichrome heating element has very high resistance compared to the low-resistance copper cord, so it gets hot enough to glow. R directly and correctly explains A. Always check if R is the correct explanation, not just both being true.