American Society of Radiologic Technologist (ASRT) Practice Exam

Disable ads (and more) with a membership for a one time $2.99 payment

Prepare for the American Society of Radiologic Technologist Exam. Use our quizzes with multiple-choice questions to assess your knowledge and understanding. Get ready for your certification with detailed explanations and exam insights!

Each practice test/flash card set has 50 randomly selected questions from a bank of over 500. You'll get a new set of questions each time!

Practice this question and more.

What must be present for current to flow?

Voltage
A vacuum
Resistance
Potential capacitance

The correct answer is: Voltage

For current to flow, voltage is a crucial component because it serves as the force that pushes the electrons through a circuit. Voltage can be understood as the electrical potential difference between two points. When there is a sufficient voltage, it creates an electric field that drives the flow of charge carriers (such as electrons) from the negative terminal to the positive terminal of a power source. In a circuit, even if resistance is present—because ohmic materials will allow current to flow up to a certain limit—what ultimately initiates the flow is the voltage. Without voltage, there is no trigger for the electrons to move; hence, no current can be established. Though resistance and other factors like capacitance may impact how much current flows, voltage remains the essential element that initiates the current flow in the first place.