AC Fundamentals Check

1. Ohm's law states:

V = I / RV = I × RP = V / IV = P × R

2. Why do buildings use AC instead of DC?

It's cheaper to installIt travels long distances efficiently with transformers, and motors run well on ACDC is unsafeAC uses less power

3. Power factor is the ratio of:

Real power to apparent powerVoltage to currentEnergy to powerWatts to joules

4. A poor power factor (say, 0.7) means:

The building is using less energyMore current is drawn than needed, wasting energy and incurring utility penaltiesThe voltage is too highThe building is very efficient

Knowledge check