Read the statements given below and choose the correct options: Assertion (A):…

Concept: A bulb filament material must satisfy two properties together: (i) an extremely high melting point, so the wire does not melt at the white-hot temperatures needed to emit light, and (ii) sufficiently high electrical resistivity, so the heating effect of current (H = I²Rt) generates enough heat to raise it to incandescence.

Application: Tungsten has the highest melting point of any metal (about 3422°C), so a tungsten wire glows white-hot without melting or vaporising quickly — this makes Assertion (A) correct. The stated Reason (R), however, claims tungsten has low resistance. In fact tungsten’s electrical resistivity is comparatively high (well above good conductors such as copper or silver), and it is exactly this high resistivity that lets the flowing current heat it enough to glow. Since the reason’s claim about resistance is factually wrong, Reason (R) is false.

Cross-check: For a wire of the SAME length and thickness, a much lower resistivity would give a much lower resistance. This matters practically: to make a wire glow, ordinary good conductors such as copper or silver would need to be made impractically long and thin to develop enough resistance to heat up when connected in a bulb circuit — which is precisely why they are never used as filaments, and why materials with naturally higher resistivity (like tungsten) are chosen instead, at a workable, durable wire thickness. This confirms R’s premise about resistance is the wrong way round, even though the high-melting-point half of R is true. Hence Assertion is true, but Reason is false.