When an electric furnace passes 4A current, it can produce 5.28 * 10 quartic J heat per minute. How about its electric power and resistance when the resistance wire is working?

When an electric furnace passes 4A current, it can produce 5.28 * 10 quartic J heat per minute. How about its electric power and resistance when the resistance wire is working?

P = W/t =5.28*10⁴/60 = 880(W)
R = P/I² = 880/4² = 55(Ω)

The output power is 20kW, the total resistance of the transmission line is 0.5 Ω, if the transmission voltage is changed from 400V to 2000V
When the transmission voltage is increased, the change of the power loss on the transmission line is the same
A increases by 7.68 × 10 ^ 6W
B decreased by 7.68 × 10 ^ 6W
C reduces 1200W
D reduced by 50W

Choose the third

The output power of a small hydropower station is 20kW, and the total resistance of the transmission line is 5. If the output voltage of the generator is 400V and the power is transmitted directly, what is the electric power lost on the transmission line? If the voltage is changed to 2000V, what is the electric power lost on the transmission line? When the voltage is 2000V, what is the turn ratio of the primary and secondary coils of the step-up transformer and step-down transformer?

Direct transmission: the transmission current I = P / u = 20000 / 400 a = 50 a can be obtained from P = UI, then the power loss P = I & # 178; r = 50 & # 178; × 5 W = 12500 w = 12.5 kW. If the voltage is changed to 2 000 V, the transmission current I '= P' / u 'can be obtained from p' = u 'I'

The output power of a hydropower station is 20kW, the output voltage is 400V, the total resistance of the wire is 0.5 ohm, how much is the power loss of the transmission line
The output power of a hydropower station is 20kW, the output voltage is 400V, and the total resistance of the wire is 0.5 ohm. What is the power loss of the transmission line? What is the electric power that users get? What is the voltage that users get?

P=UI
20kw=400V x I
I=50A
The output current is 50 a
The power loss of transmission line is: P = I ^ 2R = 50ax50ax0.5eu = 1250W
The voltage drop on the transmission line is u = IR = 50ax0.5eu = 25V
The voltage that users get is 400V = 25V = 375v