In an ac circuit power is given by:
where Vrms is the rms voltage and Irms is the rms current and
Now, ϕ is constant for a particular ac connection. If Power is constant, rms current and rms voltage have an inverse relation. Thus, higher voltage means lower current. Thus, this option is correct.
We have established that we get a lower current. Now, the power dissipated (not the net power supplied by the source) through the transmission wires of resistance R is given by:
As I is lower, Pdissipated is also less. Hence, this option is correct.
Making the transmission lines thinner is not a good idea. As resistance is inversely proportional to area, the resistance will increase. Hence energy dissipated will also increase( ). Thus, this is incorrect.
This is true. We can use transformers to increase or decrease voltages and decrease or increase current respectively. This is correct.
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