The current in a 960 W, 240 V heater operated at 200 V is

The current in a 960 W, 240 V heater operated at 200 V is 

(A) 0.25 A

(B) 0.3 A

(C) 2.5 A

(D) 3.33 A


Ans:(B) 0.3 A


Explanation :

Here  Voltage V= 240 

Power P = 960 W

Operated Voltage = 200

Current I = ?


Resistance R = V2/P

                       = (240)2/960

                       = 57600/960

                       = 60 Ohm

 

Current I = Applied Voltage / Resistance

                 = 200/60

                 = 3.33 A

 

 


The power rating of a motor drawing a current of 40 A at 400V is 

(A) 16000 W

(B) 400 W

(C) 10 W

(D) 0.1 W


Ans: (A) 16000 W


Explanation : 

Here Current I = 40 V 

Voltage V= 400 

Power ratting P = ?


Power = Voltage * Current 

           = 400 * 40 

           = 16000 W 


so Here the rating of Motor is 16000 W.





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