Question

to reduce wasteful conversion to energy, a step - transformer is used to dramatically voltage for transmission through power lines.

Explanation:

Step1: First blank

In power transmission, when current flows through wires, due to resistance, electrical energy is converted into thermal energy (heat) which is wasteful. So the first blank is "thermal".

Step2: Second and third blanks

A step - up transformer is used. The formula for power loss in transmission lines is \(P_{loss}=I^{2}R\). Power \(P = VI\) (assuming power \(P\) is constant for power generation). If we increase the voltage \(V\) (using a step - up transformer), the current \(I=\frac{P}{V}\) will decrease. Since \(P_{loss}\propto I^{2}\), the power loss will be reduced. So a step - up transformer is used to increase the voltage. So the second blank is "up" and the third blank is "increase".

Answer:

thermal, up, increase