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Figure 10.5.2 10.5. 2: (a) When an ammeter is used to measure the current through two resistors connected in series to a battery, a single ammeter is placed in series with the two resistors because the current is the same through the two resistors in series. (b) When two resistors are connected in parallel with a battery, three meters, or three ...
The leads are then attached to the ends of whatever resistance is to be measured. Since current can flow either way through a pure resistance, there is no polarity requirement for attaching the meter leads. The meter’s battery sends a current flow through the unknown resistance, the meter’s internal resistors, and the current meter.
A meter is any device built to accurately detect and display an electrical quantity in a form readable by a human being. Usually this “readable form” is visual: motion of a pointer on a scale, a series of lights arranged to form a “bargraph,” or some sort of display composed of numerical figures. In the analysis and testing of circuits ...
10.1 How Meters Measure Electrical Quantities. A meter can only measure current flow and then use that value to calculate and dis-play electrical quantities of voltage, current, and resistance. The amount of current . that can enter a meter’s circuitry is very small relative to the values found in live cir-cuits that are measured.
- Low Resistance Measurement
- Ohmmeter
- High Resistance Measurement Method
- Wheatstone Bridge
We can determine an unknown resistance in Figure 1 by applying Ohm’s law to the readings obtained from the voltmeter and ammeter. This method requires that the unknown resistance is connected into a special circuit with two separate meters. This method is useful for measuring very low resistances, such as those of motors, and for measuring the resi...
For quick checks of circuit resistance, we can use an ohmmeter, a meter designed to measure resistance directly. The simple ohmmeter showed in Figure 2(a) consists of a 1.0-mA movement, a 4.5-V battery, and a resistance that passes a 1.0-mA current when we short-circuit the ohmmeter terminals. A portion of the total resistance is adjustable so that...
When we wish to measure a very high resistance, such as the leakage between the two conductors of a cable as in Figure 4, we use a voltmeter and a separate voltage source. This system has the added advantage of testing the resistance with the normal operating voltage applied. Figure 4 Using a voltmeter as a high-resistance ohmmeter Example 3 The vo...
For precision resistance measurements, we can use a Wheatstone bridge as shown in Figure 5. If we adjust Ry such that there is no deflection of the galvanometer G when we close the switch, the voltage drops across Rx and RA must be exactly the same since a potential difference across the galvanometer would cause current to flow through the galvanom...
May 2, 2019 · *Note: Each meter will look different and have their own max values, this image is just an example and not a direct representation of every meter. Resistance measurements can be affected by other components within a circuit. The only reliable way to measure resistance is to remove the component from the circuit completely and test it.
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Can a meter be used to measure resistance?
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The resistivity of a material is a measure of how strongly a material opposes the flow of electrical current. The symbol for resistivity is the lowercase Greek letter rho, ρ, and resistivity is the reciprocal of electrical conductivity: ρ = 1 σ. The unit of resistivity in SI units is the ohm-meter (Ω ⋅ m.
