An electric heater of resistance 8 ? draws 15 A from the service mains 2hrs.Calculate the rate at which heat is developed in the heater.
Asked by saif abbas | 11th Sep, 2010, 04:59: PM
Expert Answer:
Heat generated per unit time (i.e., power, as in Watts, Joules per second) is given by
P = VI =RI2 where V is the voltage across the wire (Volts),
R is the wire resistance (Ohms), and
I is the current (Ampere).
Therefore, amount of heat generated in time t
= RI2t
= 8 x (15x15) x (2x60x60) [assuming resistance is 8 ohms. u didnt give the unit]
= 12960 kJ
Heat generated per unit time (i.e., power, as in Watts, Joules per second) is given by
P = VI =RI2 where V is the voltage across the wire (Volts),
R is the wire resistance (Ohms), and
I is the current (Ampere).
Therefore, amount of heat generated in time t
= RI2t
= 8 x (15x15) x (2x60x60) [assuming resistance is 8 ohms. u didnt give the unit]
= 12960 kJ
Answered by | 11th Sep, 2010, 07:01: PM
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