Answer:
Watts=Volt*Amps
So A=570/120=4.75amps
If voltage drops to 110V We get A=570/110=5.(18...)amps
4.75A, 479W
The power P, taken by an appliance is related to the current I, drawn by the appliance and the voltage V, at which it is operating as follows;
P = I x V -------------------(i)
From the question, the appliance is the electric heater and;
P = 570W
V = 120V
Substitute these values into equation (i) as follows;
570 = I x 120
i = [tex]\frac{570}{120}[/tex]
I = 4.75
Therefore, the current that it draws is 4.75A
(b) First, lets find the resistance, R, in the heater as follows;
P = [tex]\frac{V^{2} }{R}[/tex] -----------------------(ii)
Where;
P = Power
V = Voltage
Substitute V=120V and P=570W into equation (ii) as follows;
570 = [tex]\frac{120^{2} }{R}[/tex]
Cross multiply and solve for R;
570R = 120²
570R = 14400
R = [tex]\frac{14400}{570}[/tex]
R = 25.26Ω
The resistance of the heater is 25.26Ω
Now, if the voltage drops to 110V and resistance is assumed to be constant, then using equation (ii);
P = [tex]\frac{V^{2} }{R}[/tex]
...we can calculate the power the heater takes by substituting V=110V and R = 25.26Ω as follows;
P = [tex]\frac{110^{2} }{25.26}[/tex]
P = 479
Therefore, the power the heater takes is 479W
