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Question
A toaster produces more heat than a light bulb when connected in parallel to a 220V mains. Which one has a greater resistance. Please give detailed explanation.
A toaster produces more heat than a light bulb when connected in parallel to a 220V mains. Which one has a greater resistance. Please give detailed explanation.
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Solution
3 answers · Physics
Best Answer
Electrical heating comes from the power dissipated in a resistor, given by P = I^2 * R (where P=power, I=current, R=resistance). Also, V=IR; this can be rearranged to state I=V/R. This can be substituted into the equation for power to state:
P = I^2 * R
=(V/R)^2 * R
=V^2/R
Power is inversely proportional to resistance at constant voltage. Therefore, for circuits connected to a constant voltage source (the 220 volt mains), the one with the lowest resistance will have the highest heat. If the toaster gets hotter, it has lower resistance.
Best Answer
Electrical heating comes from the power dissipated in a resistor, given by P = I^2 * R (where P=power, I=current, R=resistance). Also, V=IR; this can be rearranged to state I=V/R. This can be substituted into the equation for power to state:
P = I^2 * R
=(V/R)^2 * R
=V^2/R
Power is inversely proportional to resistance at constant voltage. Therefore, for circuits connected to a constant voltage source (the 220 volt mains), the one with the lowest resistance will have the highest heat. If the toaster gets hotter, it has lower resistance.
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