Answers

2015-06-07T13:42:50+05:30
Voltage = current × resistance [from V = IR relation ]
V = 2 × 10 = 20 volts
We know, P = VI
P = 20 × 2 = 40W
We know, Power = Work/Time
⇒ Energy = Power × Time = 40 × 30 ×60 = 72000J = 72 KJ 

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2015-06-07T14:13:35+05:30
Acc. to Ohm's law
V = IR 
V = 2 × 10 = 20 volts
We know, P = VI
P = 20 × 2 = 40 Watts
We know, Power = Energy/Time
So, Energy = Power × Time = P x t = 40 × 30 × 60 = 72000Joules = 72 Kilo Joules 
0
Voltage = current × resistance
V = 2 × 10 = 20 volts
As, P = VI
P = 20 × 2 = 40W
We know, Power = Work/Time
⇒ Energy = Power × Time = 40 × 30 ×60 = 72000J = 72 KJ