Transformers are used to increase the voltage produced at power plants. Why is it desirable for the power to be transmitted at high voltage?
(a) the the transformer induction will be less resulting in less joule heating
(b) then the resistance of the wires will be less resulting in less joule heating
(c) then the current will smaller resulting in less joule heating.
(d) then the speed of transmission will approach the speed of an EM wave (c).
The ans. is C.
The correct answer is (c) then the current will be smaller resulting in less joule heating.
When power is transmitted over long distances, it is essential to minimize energy losses. One significant source of energy loss is joule heating, which occurs when electric current passes through a conductor and generates heat due to the resistance of the wire.
By using transformers to increase the voltage at power plants, the current in the transmission lines can be reduced for the same amount of power being transmitted. According to Ohm's Law (V = I x R), for a given power, decreasing the current (I) would result in a decrease in the resistance (R) required to maintain the same voltage (V).
Lowering the current reduces the amount of energy lost due to joule heating since the amount of heat generated is directly proportional to the square of the current, as expressed by the equation P = I^2 x R. Therefore, by increasing the voltage and reducing the current, power transmission becomes more efficient, resulting in fewer energy losses.
It's worth noting that option (a) is not correct because the induction of a transformer is not directly related to joule heating. Option (b) is not correct because the resistance of the wires remains the same regardless of the voltage level. Option (d) is not correct because the speed of transmission is not dependent on the voltage but rather on the properties of the transmission medium.