Question

If there is no current in the circuit, then a voltmeter connected across a resistor will register ................ voltage.
(A) Zero
(B) High
(C) Low
(D) Infinite

Answer 1

Hint We solve this problem by using the definition of ohm's law. Ohm's law gives a relation between current voltage and resistance in a given system. Using this we find the voltage across the resistor. A voltmeter is a device that measures the voltage across two points. By finding the voltage difference between the resistor we find the reading in the voltmeter, which is what is asked in the question.

Complete Step by step answer
We know that according to ohm's law voltage is equal to the product of the magnitude of current and resistance. From the question, we know that there is no current in the circuit which means the current is zero. We can now say that the voltage between the resistor will also be zero because the product of current(zero) and the resistor is equal to zero.
Hence the voltmeter reading will be zero.

Option (A) zero is the correct answer.

Additional information The voltmeter was invented in the year 1819 by a scientist named Hans Oersted. He invented the first most simple voltmeter. There are two types of voltmeters based on outputs provided: Digital Voltmeter and Analog Voltmeter.

Note A voltmeter is a device that measures the potential difference between two points. It is connected in parallel with a system to find its voltage. This is because in a parallel circuit current varies and voltage remains equal. In the case of a series circuit, the voltage varies but the currents remain constant. This is the reason why an ammeter is connected in series with a device to find the current.