Reading a voltmeter involves a needle pointer (for analog voltmeter) on the scale to indicate the voltage difference. In the case of a digital voltmeter, the reading of the voltage value will be exact in precise number.
Here are other four things we’ll discuss in the post:
- Analog voltmeter reading
- Digital voltmeter reading
- Reading amplified voltmeter
Analog voltmeter reading
You got a voltage scale on the needle’s dial and chose the right setting that matches the one on your voltmeter’s knob. Otherwise, use a reading from a scale that has easy multiple settings.
For instance, you can use a DC scale with a maximum reading of 50 or 10 if the setting on the voltmeter is DC 10V.
You have to estimate the position of the needle according to the adjacent numbers. For instance, when the needle pointer is between 20 and 30, the reading indicated is 25V. The linear scale resembles a ruler, and it is easy to read.
If the scale in use is different, then divide your answer. Take the scale’s maximum printed value and divide it with your knob setting.
In turn, take the number the needle points to and divide it with your answer to obtain the actual voltage.
A galvanometer can be used as a voltmeter when the resistor is connected with other instruments in series.
Torque is created due to the interaction of the stationary magnet and the coil’s magnetic field when the current is applied.
The current is proportional to the torque via the coil, whereby it rotates, causing opposition due to the spring compression.
The coils deflection is promotional to the voltage applied and current. The pointer on the scale displays the voltage.
There is a response to one direction on a permanent magnetic field when moving-coil instruments.
For coil deflection to be obtained, you need to use a rectifier when measuring AC voltage in a circuit to obtain the reading on the voltmeter.
Electrostatic voltmeters deflect a pointer due to mutual repulsion that is created by the charged plates.
This voltmeter works with either DC or AC currents and is sensitive to high voltages even though the current they draw is negligible.
Digital voltmeter reading
First, set the voltmeter to measure voltage. Set your device to test either DC circuit or Ac circuit voltage. You can avoid voltmeter damage by changing the device’s sensitivity to obtain a good measurement reading.
Your voltmeter has one red and one black test lead; therefore, insert the leads. There is a metal jack for each lead on one end and a metal probe on the other side. Plug the blackjack into the “COM” labeled hole and the red jack into the V labeled hole.
The probes should be held with safety; thus, do not touch them when making the connection to the circuit. Avoid bringing the metal probes into conduct when in circuit connection to avoid severe sparking.
Make a parallel attachment of the test leads to test the voltage of the circuit. It means that in a closed circuit, attach the metal probes to two different points when already there is currently flowing through it.
Complete the circuit by attaching the red test lead to a different point of the circuit. This will cause the voltage to be displayed on the device.
When using a battery, the positive terminal should be connected to the red test lead, and the in-wall outlet should be connected to “hot” a small hole located on the right side.
If you get an overload value, raise your voltmeter range before your voltmeter gets damaged. If the display on your reading shows “1” or “OL,” and if the scale pointer needle moves to the opposite side of the scale for the analog voltmeter, then your device is at risk of getting damaged.
If there is no reading displayed on your analog voltmeter or reading on your digital display shows nothing or reads 0V, you have to adjust your voltmeter accordingly.
Ensure you connect well the test probes to the circuit if necessary, repeat one range setting reduction until the real reading is achieved.
At this stage, the voltage reading will be displayed on the digital voltmeter screen.
Reading amplified voltmeter
You need Ohm’s law so that the current reading can be interpreted in terms of resistance and voltage. The amplifier of the voltmeter is sensitive to voltage; thus, the current measurement for the input circuit will be converted to corresponding levels voltages and interpret the flowing current using ohm’s law.
Conclusion
Voltmeter reading involves:
- Needle pointer on the scale to indicate the voltage difference (analog voltmeter)
- In a digital voltmeter, the reading of the voltage value will be exact in precise number.
- Electrostatic voltmeters deflect a pointer due to mutual repulsion that is created by the charged plates.
- The amplifier of the voltmeter amplifiers is sensitive to voltage, so the current measurement for the input circuit will be converted to volts for each level.