A transformer is given a test at what voltage if the test is 90 kilovolts?

In testing transformers, the voltage applied is typically determined by the specifications of the transformer system and the testing standards being followed. In this case, a test voltage of 90 kilovolts is explicitly mentioned. Since the term "kilovolt" translates directly into thousands of volts, 90 kilovolts amounts to 90,000 volts.

Choosing 90,000 V is correct because it represents the exact conversion of kilovolts into volts: 1 kilovolt equals 1,000 volts, thus 90 kilovolts equals 90,000 volts (90 x 1,000). This testing voltage is significant as it helps assess the transformer's insulation and overall integrity under conditions simulating normal operational stresses, allowing for reliable performance assessments in real-world applications.

The other options do not align with the provided voltage specification of 90 kilovolts, which is critical for ensuring accurate testing and evaluation of transformer performance.