Why is the dial of a pointer multimeter marked 0Ω?
Pointer multimeter ohm file has three key points both: 0Ω, ∞ and the centre value. Because the ohm file itself is equipped with a battery, when the pen short-circuit resistance of zero, the current through the head of the largest, at this time with the zero potentiometer to adjust the pointer to the full value, we artificially defined here as the zero position.
After the pen is separated we regard the resistance between the two pens ∞, at this time there is no current through the head, so the pointer does not move, this position is marked ∞.
It is the centre of the ohm gear value of 16.5 in different gears multiplied by their respective coefficients on behalf of the central position of the resistance value, such as Rx1 on behalf of 16.5Ω, R x 10 for 165Ω, R x 100 for 1650Ω, Rx1K for 16.5KΩ, Rx10K 165KΩ.
The centre scale value is very important, it marks the range of resistance measurement of the gear, for example, Rx1 is most suitable for measuring 16.5 as the centre of a few Ω to a few hundred Ω resistance, Rx1K is suitable for measuring a few K to a few hundred K Ω. When we measure the 100 Ω resistance, the Rx1 gear pointer is only deflected by about 1 / 6, see more clearly. Measured with 10K, the pointer is still basically pointing to the 0Ω position. Difficult to observe the subtle changes in the pointer. This shows that the same 0 Ω in the measurement of the same resistance, different gears of the pointer deviation is not the same.
At the same time, the centre of the ohm gear scale is also the internal resistance of the multimeter of this gear, interested friends can also measure their own. Specific measurement method is to take out the battery of the pointer multimeter, the battery clip will be shorted with a wire, and then find a digital multimeter can be measured directly.
