Step-up transformers affect voltage and amperage in which of the following ways?

A step-up transformer is designed to increase voltage while decreasing current in an electrical circuit. This is based on the principle of conservation of energy, which states that power (expressed as the product of voltage and current) must remain constant in an ideal transformer without losses. When voltage is stepped up, the transformer essentially allows a higher voltage to be delivered to the output side compared to the input side.

For example, if a transformer increases the voltage from 100 volts to 400 volts, the current on the output side will consequently decrease to ensure that the power remains constant. This relationship can be illustrated by the formula:

Power (P) = Voltage (V) x Current (I).

So, if the voltage increases, the current must decrease proportionally. This makes the option that states "increase voltage and decrease amperage" the correct one, illustrating the fundamental behavior of step-up transformers in electrical engineering.