How is a voltmeter used in a circuit? A. It is connected in series and measures current.
B. It is connected in parallel and measures potential difference.
C. It is connected in parallel and measures current.
D. It is connected in series and measures potential difference.

Explanation:

A voltmeter is usually connected in parallel with a part of a complete circuit.  The meter itself is connected in series to a very high resistance so that the amount of current drained is very tiny.

So you see, you could answer this in two ways, but since you are asking a question at a very beginning level, I think the answer should be

B

because voltmeters are made to measure potential difference and they are placed in parallel to the part measured. How it works is interesting but is not really part of the question.

B. It is connected in parallel and measures potential difference.

Explanation:

A voltmeter is connected in parallel.

A voltmeter is used for measuring the electrical potential difference between two points in an electric circuit.