What is the formula for calculating running costs for electrical appliances?

The formula for calculating running costs for electrical appliances indeed centers on understanding how much electricity an appliance consumes and the cost associated with that consumption. The correct answer involves multiplying the amount of power used, measured in kilowatt-hours (kWh), by the cost of electricity per kilowatt-hour ($/kWh).

When you multiply power usage (in kWh) by the cost of electricity, you determine the total running cost of the appliance over a specific period. This approach provides a straightforward method for estimating expenses related to electrical appliances based on their energy consumption and the rate you are charged for electricity.

While other options mention essential concepts of electricity (like power, voltage, and current), they do not directly lead to calculating the running costs in a manner that relates to billing from your electricity supplier. Power usage (in kW or kWh) and the cost per unit of energy are specifically tailored to give the financial impact of using electrical devices.