Question

Why are transformers used in the transmission of electric power?
This question has multiple correct options
A) Because they can reduce transmission losses
B) Because they can conserve electrical energy
C) Because they speed up transmission
D) Because they help to distribute electrical energy efficiently

Answer 1

Hint The energy losses in transmission are ohmic power losses associated with the current flowing through the circuit and the resistance of the wires in the transmission line. Lower current in the wires implies lower power losses and vice versa. Higher voltages will require more insulation and hence increase costs.

Complete step by step answer
Transformers are devices that can increase or decrease current or voltage that is being transmitted through the transmission lines in the form of alternating current.
To reduce costs in the transmission lines, we require the minimum amount of energy losses in the transmission lines. So ideally we can increase the voltage of the power lines $ (V) $ and since the power transmitted in the lines remain constant, from the relation $ P = VI $ , the current $ (I) $ transmitted in the cables will decrease and hence the ohmic energy losses due to the resistance of the cables will decrease and we will save energy which is mentioned in option (A) and (D).
However, transmitting higher voltage through the power lines requires more insulation on the power lines and increases the costs once again. So, to minimize energy losses and costs, we need to decide an optimal amount of voltage and current to be transmitted in the lines.
To convert the alternating current to have a specific amount of voltage and current in the transmission lines, we must use transformers to step-up or step-down the current or voltage.
From the above discussion, we can conclude that option (A) and option (D) are correct.

Note
We can also rule out option (B) since transformers are not needed to conserve electrical energy as there will always be energy losses associated with actual transformers as well as power transmission lines and we can never completely conserve electrical energy. Similarly, we can also rule out option (C) since the transmission speed of the current in the power lines is constant and travels near the speed of light and it is independent of the voltage or current in the power lines, which is controlled by transformers.