Alternating Currents

Question 1

Define AC peak value.

Answer 1

Highest instantaneous current/voltage reached by AC.

Question 2

Define Root Mean Square value.

Answer 2

The value of direct current/steady voltage, producing equivalent power in a resistor/an appliance to an AC.

Question 3

Define a Transformer.

State what is meant by a “step-up/-down” transformer.

Answer 3

A device used to alter voltage/current of an AC while conserving P.
Step-up: N(p) < N(s), so V(p)

Question 4

Define Eddy Currents.

Answer 4

Currents due to induced EMF in a metallic conductor in a changing magnetic field.

Question 5

State the benefits of using high V AC for long-distance electricity transmission.

Answer 5

High V: less current needed for high P transfer, so less power loss to heating;
AC: output V efficiently changeable via transformers, also generated directly, so no P loss pre-sending due to rectification.