Ohmmeter Series type | Electrical Instruments ( EIM ) | Lec - 12

Electrical Instruments ( EIM )
Series type ohmmeter : meter connection with unknown resistor
Lec-11 : • AC voltmeters | Using ...
Lec-13 : • Ohmmeter Shunt Type | ...

[@msaglawani6324]

Best explanation

[@harith_khaleel]

Hello sir... Thank you so much I only have one question... What is the point of having Rh... I don't really get it if you can... Explain it a little bit more please ❤❤

[@abdullahmohammad3527]

When using an ohmmeter, an external resistor called "Rh" is used to expand the measuring range of the device. This resistor acts as an adjustment factor to determine the range of resistances that can be measured by the device. When you want to measure resistance, the terminals of the ohmmeter are connected to the ends of the resistor. A specific voltage is applied to the resistor, and the current flowing through it is measured. Then, the basic Ohm's law can be used to calculate the resistance value using the measured values of voltage and current. But the problem is that the measuring range of the ohmmeter is not unlimited. Therefore, a specific external resistor (Rh) must be connected to the ohmmeter. The value of this resistor is determined so that the ohmmeter can measure a specific range of resistances. For example, if the resistance value to be measured is higher than the value of "Rh", an accurate reading of the resistance will not be obtained. And if the resistance is less than the value of "Rh", the device may be damaged or the measurements may be destroyed. Therefore, using "Rh" in the ohmmeter helps to determine the range of resistances that can be accurately measured by the device and expands the measuring range of the device. Thus, it helps to improve the accuracy of the measurements.