Question

The electricity that is delivered to our homes from regional generating stations moves over transmission lines that are _____.

high voltage and low current
high voltage and high current
low voltage and high current
low voltage and low current

Answer 1

high voltage and low current

Step-by-step explanation:

Electricity is transmitted over transmission lines at very high voltages and low current.

The reason for this choice is to minimize the power dissipated along the transmission line. In fact, the dissipated power is given by:

`P_(d) = I^2 R = (P^2)/(V^2)R`

where

Pd is the dissipated power

I is the current

R is the resistance of the cables

V is the voltage

P is the generated power

From the first formula, we see that the dissipated power is proportional to the square of the current, so in order to minimize the loss of power, it is better to use low current. Moreover, from the second formula we see that the dissipated power is inversely proportional to the square of the voltage, so the higher the voltage, the less the power dissipated along the transmission lines.

Answer 2

The third option is the answer. low voltage and high current.
From regional transmission, electricity distributed to our homes is in low voltage and high current.
Electricity from main power house is step up to higher voltage to reduce the losses of energy and then step down to lower voltage in regional transmission house.