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 ▸What happens to the pressure inside a gas-filled ball when the temperature is increased? Explain your answer, stating the assumption made.
A 1kg spring has an unloaded length 10cm and has an elastic constant of 100N/m. It is compressed to 6cm then placed facing upwards on the floor. When released it travels vertically upwards. How high does it jump? You may assume no energy is lost to heat o
What is the optimum angle to throw a snowball for maximum horizontal displacement? (Ignore air resistance, assume the snowball is thrown level with the ground. The angle is measured from the ground up)
Topic - force as rate of change of momentum; (i) force on a wall due to water from a hose, (ii) force on a table as a rope is dropped onto it.