a toaster produces more heat than a bulb when connected in parallel to the 220v mains.which of the two has greater resistance and why?

Asked by sonali garg | 22nd Jun, 2013, 08:08: PM

Expert 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
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. Hence, bulb will have higher resistance. 

Answered by  | 23rd Jun, 2013, 05:52: AM

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