What is an ohmmeter center resistor? What is the use of a median resistance in an ohmmeter?

The ohmmeter is an instrument for measuring resistance, Figure 1 is the measurement principle of the ohmmeter, G is an ammeter with internal resistance for RG and full-scale current for IG, and R is a variable resistance, also called zeroing resistance; The battery is a dry battery, the electromotive force is E, the internal resistance is R, and the red pen (inserted into the "+" jack) is connected to the negative pole of the battery; The black watch pen (inserted into the "-" jack) is connected to the positive pole of the battery when the resistance rx is measured

R is small and negligible compared to RG and R.

From equation (1), it can be seen that there is a one-to-one correspondence between a given ohm table i and rx, so the size of rx can be known from the position of the header pointer

The total internal resistance value of the ohmic meter.

When the measured resistance value is equal to the internal resistance of the multimeter, the current is half of the full bias current. Because the pointer is in the middle, it is called the median resistance.

The value of the resistance and the rx of the ohmic meter correspond to the value of an i ig, which is the only value that determines the position of the watch hand When i ig=1, the watch hand refers to the rightmost end, and when i ig=1 2, the watch hand refers to the center of the dial.

Each rx determines the value of an i ig, and each i ig determines the position of a watch hand, if two ohmic meters have different (r+rg) values, the same rx corresponds to a different i ig, i.e. corresponding to a different position of the watch hand.

Their scales are not the same, and vice versa; Only two ohmic watches (r+rg) have the same value, their scales are exactly the same, (you can share a dial), ohmic (r+rg) is called its median resistance, that is, the median resistance only determines the ohmic dial.

The meter head and the gear adjustment resistor are connected in parallel. After that, it is connected in series with the resistor to be measured. If the resistance to be measured is 1K for the first measurement, the ohmmeter is just right with the A stop.

When the second measurement, the resistance to be measured is 1m, if you do not change gears, still use the A gear, that is, do not change the internal resistance of the ohmic meter, then, the current passing is very small, and the deflection is relatively small. In order to increase the current of the meter head, you can only change the gear adjustment resistance connected in parallel with it, and when the gear adjustment resistance is increased, the current passed by the meter head increases, and the deflection increases, which is convenient for reading.

Increasing the magnification is also to increase the Zheng shouting gear resistance, and the resistance after the gear adjustment resistance and the meter head are connected in parallel is increased, that is, the internal resistance increases.

The central resistance of the ohmmeter is equal to the internal resistance of the ohmmeter and is determined by dividing the voltage of the ohmmeter cell by the full scale of the current.

Suppose ohms use a dry cell battery, take e = and let the range of the current be i at this time, then the median resistance r = e i. Because the internal resistance of the battery is much greater than the conductor resistance, the conductor resistance in the meter is negligible.

When the measured resistance value is equal to the internal resistance of the ohmmeter, the current is half of the full bias current, that is, the pointer is in the positive **. The central resistance is the internal resistance of the ohmic meter.

Summary. An ohmmeter is a DC resistance measuring instrument, and a resistance meter is an AC resistance measuring instrument.

An ohmmeter is a DC resistance measuring instrument, and a resistance meter is an AC resistance measuring instrument.

Can you tell us more about that?

Both the Euroband Meter and the Resistance Meter are instruments used to measure resistance, but they differ in their working principles and uses. The Ohm Good Strike Meter is a DC resistance measurement instrument that works by using Ohm's law to calculate the resistance value by measuring the ratio of current and voltage. Ohmmeters are often used to measure the value of resistance in a circuit to determine the operating condition of the circuit and the cause of the failure.

Resistance meter is a kind of AC resistance measurement instrument, which works by using AC resistance measurement technology to calculate the resistance value by measuring the phase difference of AC current and voltage in a circuit. Resistance meters are commonly used to measure the resistance values of components such as high resistance, low resistance, and rheostats. Therefore, the difference between an ohmic meter and a resistance meter is that they work differently and use the different scenarios.

The central resistance of the ohmic meter is the internal resistance of the ohmic meter.

When the state model watch pen is short-circuited, the pointer is full of scale, because only the internal resistance of the watch exists; When an external resistance value is equal to the resistance of the internal resistance of the meter, because the battery voltage has not changed, now the overall number of sails has become 2 times, so the current is halved, and the pointer must point to the middle, which is called the central Bivolt resistance value.

Well. What you said earlier is yes.

As for the resistance ... Let's break it down.

Why can an ohmmeter measure resistance? It is nothing more than an ammeter converted.

We know that both voltmeter and ammeter are both the greater the current and voltage, the greater his offset, while the ohmmeter is the opposite, the greater the resistance, the smaller the offset, why is this? Because r=u i, because the voltage is constant, so our ohmmeter needs to add power for this reason, which is just to change the ammeter and add a resistor. He helped you calculate the result, that's it, you can measure the resistance value with the ammeter, but you have to calculate it, which is the previous formula to calculate.

Changing the magnification is what to change, that is, changing the resistance, that is, connecting an electronic resistance in series. Causes its resistance value to change, thus affecting its magnification.

If you don't understand, you can ask again.,Thank you.。。

The working principle of the ohmmeter is: when connected to the same power supply and kept the voltage unchanged, the greater the resistance in the access circuit, the smaller the current in the circuit, that is, the resistance is increased by two times and the current is reduced by one. Therefore, when measuring the resistance, there is a full bias current and a half bias current.

Therefore, before measuring the resistance, the two gauge hands should be in direct contact so that the ohmic meter is fully offset. Therefore, there is a power supply, a protection resistor, and a rheostat in the ohmmeter, and the sum of their resistances is called the internal resistance rAt this time, the full bias current i u r, when the ohmmeter is connected to the measured resistance r, the current i' u (r+r), when r r, i' i 2, that is, the measured resistance r is equal to the median resistance.

Changing the magnification is to change the rheostat in the ohmmeter, so as to change the internal resistance r, that is, the median resistance In short, when the magnification is unchanged, the electromotive force of the ohmmeter power supply is constant, the internal resistance r is unchanged, the full bias current of the meter head is certain, and the median resistance is also certain;

The magnification changes, the electromotive force of the ohmmeter power supply is constant, the internal resistance r changes, the meter head is full polarized current, and the median resistance changes; The magnification is different, the electromotive force of the ohmmeter power supply is the same, the internal resistance r is different, the full bias current of the meter head is different, and the median resistance is different.

Electronic ohms can do any electronic calculation, so you can do anything.

The ordinary ohmmeter is nothing more than a series of resistors to be measured, and then measure the current of the parallel resistance, by connecting different resistors in series, it is easy to make the same potential, the current unit is not the same.

Are you asking about the modification of the meter?