- The voltage travelling away from a power plant through transmission lines is very high, and it is typically of hundreds of kilovolts (typical values are between 138 kV and 765 kV).
- The main reason to use these high values of voltage is to reduce power dissipation.
In fact, the cables that are used to transmit electricity have a certain resistance R which is fixed. The power generated from the power plant and that should be transmitted through the lines is P, and it is also fixed.
The power dissipated through the cables is calculated as

where I is the current and V the voltage.
As it can be seen, using higher voltages reduce the amount of power dissipated through the lines (while using higher currents will have the opposite effect).
The efficiency of the process is 42%
From the question given above, the following data were obtained:
Useful energy = 250 watt
Wasteful energy = 600 watt
<h3>Efficiency =? </h3>
The efficiency of the process can be obtained as illustrated below:

<h3>Efficiency = 42%</h3>
Therefore, the efficiency of the process is 42%
Learn more: brainly.com/question/2300041
Answer:
Work done, W = 5534.53 J
Explanation:
It is given that,
Force acting on the piano, F = 6157 N
It is pushed up a distance of 2.41 m friction less plank.
Let W is the work done in sliding the piano up the plank at a slow constant rate. It is given by :

Since,
(in vertical direction)

W = 5534.53 J
So, the work done in sliding the piano up the plank is 5534.53 J. Hence, this is the required solution.