In a circuit with fixed voltage, increasing a lamp's resistance will cause its wattage to

In a circuit with fixed voltage, increasing a lamp's resistance will cause its wattage to

• A. Increase
• B. Decrease
• C. Remain the Same
• D. Oscillate

Answer: (B)

With a fixed supply voltage, the lamp’s wattage is determined by P = V^2 / R. If you increase the lamp’s resistance, the current it draws drops (I = V / R). Since power equals voltage times current, a smaller current means less power is dissipated. So the wattage decreases. It won’t stay the same or oscillate under a steady DC supply.

With a fixed supply voltage, the lamp’s wattage is determined by P = V^2 / R. If you increase the lamp’s resistance, the current it draws drops (I = V / R). Since power equals voltage times current, a smaller current means less power is dissipated. So the wattage decreases. It won’t stay the same or oscillate under a steady DC supply.