An oven's broiler element has a resistance of 24 Ω and runs on a 240 V supply. P = V²/R gives the power it dissipates in one step.
P = V²/R gives the power dissipated in a resistance from the voltage across it and its resistance. The calculation runs the same three steps as every power calculation.
Step 1. Write down the values in the question, and mark the one you want.
Step 2. Write down the equation.
Step 3. Substitute in the values, and simplify. The result line carries the unit: power comes out in watts.
An oven's broiler element has a resistance of 24 Ω on a 240 V supply. Calculate the power it dissipates.
Write down the values in the question:
V = 240 V
R = 24 Ω
P = ?
Write down the equation:
P = V²/R
Substitute in the values:
P = (240)²/24
Simplify:
P = 57600/24
P = 2400 W
The broiler element dissipates 2400 W.
A 36 Ω engine heater has 120 V across it. Enter its power in watts.
A 96 Ω heated blanket has 120 V across it. Enter its power in watts.
A 240 Ω tank warmer has 120 V across it. Enter its power in watts.
The same oven's bake element has a resistance of 48 Ω on the same 240 V supply. Calculate the power it dissipates.
Write down the values in the question:
V = 240 V
R = 48 Ω
P = ?
Write down the equation:
P = V²/R
Substitute in the values:
P = (240)²/48
Simplify:
P = 57600/48
P = 1200 W
Twice the resistance, half the power: the bake element heats more gently than the broiler.
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