Question

The power transmission is carried out at ______ and ______?
A. High voltage, high current
B. Low voltage, high current
C. High voltage, low current
D. Low voltage, low current

Answer 1

Hint:In the above question, we are asked for the power transmission for which we need to know about the power loss. Because we need low power loss and that is explained by the joule’s heating effect and after observing the proportionality we can mark the correct option.

Complete answer:
Before choosing the right option, let us revive our concepts for power transmission. Transmission of electricity is the power loss in transmission lines, dissipated as heat due to resistance of capacitors. The loss in electric power flowing through the transmission lines due to resistance is called ohmic loss. The formula for power loss is,
${P_{loss}} = {I^2}R$ where I is the current and R is the resistance.
Now, if we modify the ohm’s law equation,
$P = VI$

For the proper power transmission, we all need to have less power loss. The resistance is the blockage offered to the follow of electrons but also it doesn’t affect the flow of charge.Hence, power loss is not a function of voltage.
Using the Joule’s heating effect $H = {I^2}RT$
Heat produced is directly proportional to the square of current and the resistance. We want to minimize the power loss; power transmission should be taken at high voltage and low current.

So, the correct option is C.

Note:Joules’ heating effect states that when current passes through the conductor then heat produced will be given by the product of the resistance, time and the current produced. High Voltage reduces current due to resistive loss occurring in the conductor.