1. A 2.0mm copper wire has a resitance of 1.85 ohm per thousand feet: a. calculate the power lost if the wire?

Question

is 200 feet long carrying a current of 10 amperes. b. what is the voltage difference between the two ends of the wire.

2. A one ampere fuse has a resitance of 0.5 ohm. it will melt or blow when the instantaneous current flowing through it is large enough to create a power loss of 5 watts. what is the value of the melting curent?

3. An earth ground at the base of the transmissiong line tower has a resistance of 2ohms. a. if the lightning stroke of 20,000 amperes strikes the tower, what would be the power dissipated in the ground? b. what would be the voltage drop across the ground?

4. A DC motor draws a current of 50A at 230 volts. if 200 watts is dissipated in the form of heat in the motor, how much power is available for mechanical work?

Answer 1

let V = Volts , I = Current , R = Resistance and P = power...

V = R * I

P = V * I eq P = (R * I) * I = R * I * I = R * I^2

1. A 2.0mm copper wire has a resitance of 1.85 ohm per thousand feet: a. calculate the power lost if the wire?

is 200 feet long carrying a current of 10 amperes. b. what is the voltage difference between the two ends of the wire.

R = 1.85/5, P = (1.85/5) * (10*10), V = (1.85/5) * 10

R = 1.85/5 because 200 [ft] is 1/5 of 1000 [ft.

2. A one ampere fuse has a resitance of 0.5 ohm. it will melt or blow when the instantaneous current flowing through it is large enough to create a power loss of 5 watts. what is the value of the melting curent?

5 = 0.5 * I^2 eq 10 = I^2 eq I = sqrt(10)

3. An earth ground at the base of the transmissiong line tower has a resistance of 2ohms. a. if the lightning stroke of 20,000 amperes strikes the tower, what would be the power dissipated in the ground? b. what would be the voltage drop across the ground?

P = 2 * 20,000 * 20,000 , V = 2 * 20,000

4. A DC motor draws a current of 50A at 230 volts. if 200 watts is dissipated in the form of heat in the motor, how much power is available for mechanical work?

P = (50 * 230) - 200

Good luck.