Explain why a transformer is used in electrical power lines.
Power stations use step-down transformers to decrease the voltage of the electrical output. The power lines have a constant resistance (say, R Ohms) which means there is a power loss across the lines given by P = IV. By using Ohm's law (V = IR), we can obtain the formula P = V^2 / R which shows that the power loss goes as the square of the voltage. By using a step down transformer, we can minimize the power loss that occurs during transmission.
ZM
Related Physics A Level answers
All answers ▸How do you prove Kepler's Third Law?
Using Newton's law of universal gravitation, show that T^2 is proportional to r^3 (where T is the orbital period of a planet around a star, and r is the distance between them).
Experimentally, how would you calculate the Young's modulus of a material?
Find current and voltage across resistors R1 and R2, when they connected in parallel and in series. A 12V battery is connected, R1=4Ω and R2=3Ω.