Is the internal resistance of voltage measuring devices constant?
Does the internal resistance of a voltmeter remain constant regardless of the voltage applied to the meter?
I would be very grateful for a brief explanation!
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With digital devices with automatic range switching, it is always the same
With digital devices without automatic switching, it depends on how they are built inside
In analogue pointers, it depends on the measuring range.
Everything should be in detail in the data sheet of the respective device.
In voltage measurement, the internal resistance changes with a change in the measuring range. The higher the measuring range, the higher the internal resistance.
Thank you. Is the internal resistance always constant in this measuring range? Suppose we have a voltage meter with the ranges 15V/150V. The internal resistance in the range up to 15 V is then smaller than in the range up to 150V.
Does the internal resistance also change whether you measure 120V or 150V?
The internal resistance in the selected range remains constant. Whether it's 120 or 150 volts.
Don't have to be. For example, most digital multimeters have 10MOhm, regardless of the measuring range.
It's different. In the case of analogue voltmeters, it could be quite that the measurement range changes. With digital multimeters it usually remains the same and is often 10MOhm.
If only the voltage changes and not the measuring range, the internal resistance always remains the same.