Resistance Changes in Electrical Components

Steps:

• Recall that resistance R = V/I; for ohmic components, R is constant, but non-ohmic vary.
• Evaluate A: Filament lamp heats up with higher PD, increasing resistance.
• Evaluate B, C, D: Check if their resistance rises under given conditions.
• Select option where resistance explicitly increases.

Why A is correct:

• Filament lamps are non-ohmic; increasing PD raises temperature, and metals have positive temperature coefficient, so R increases per R = ρL/A where ρ rises with heat.

Why the others are wrong:

• B: LDR resistance decreases as light intensity increases, allowing more current.
• C: Metallic conductors at constant temperature are ohmic, so R remains constant despite current change.
• D: Thermistors (NTC type) have resistance that decreases as temperature rises from current.

Final answer: A