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I assume you are referring to methods of measuring small value resistances, as in locating short circuits on a PC card.
Two probe is the method used by standard ohm meters. This works OK for most resistance values, as the resistance of the leads & probes is much lower than the resistance being measured. But when the resistance being measured gets very tiny (e.g. a few milliohms) it fails as the resistance of the leads & probe are of the same order of magnitude and are in series with it.
Four probe solves this problem by using two probes connected to a current source to drive the resistance and a separate two probes connected to a precision voltmeter calibrated in milliohms. The voltage drop in the leads due to the test current does not get measured by the calibrated voltmeter, as it does in two probe method. There is no voltage drop in the measurement leads as the voltmeter is high impedance.
What else can I help you with?
What are 3 methods used to isolate microorganisms from a mixed culture?
It is necessary to make the colonies well-isolated from each other so that each appears distinct, large and shows characteristic growth forms.Most bacteria, many other microfungi, and unicellular microalgae, may be most commonly obtained by plating methods such as streak plate method, pour plate method and spread plate method.
What are the differences between classical and spectroscopic method of chemical analysis?
Classical methods of chemical analysis involve direct measurement of properties like mass or volume to determine the composition of a substance. Spectroscopic methods, on the other hand, rely on the interaction between matter and electromagnetic radiation to analyze chemical composition. Spectroscopic methods are often more sensitive and provide more detailed information about molecular structure compared to classical methods.
Are there other planets besides the solar system?
Yes, there are other planets beyond our solar system. These planets are known as exoplanets and have been discovered orbiting other stars in our galaxy. Thousands of exoplanets have been identified so far using various methods like the transit method and radial velocity method.
What is the main advantage of pour-plate method over other methods of bacterial colony isolation?
Previous answer: "because of infection" This person is obviously trying to be funny, the right word should be "Contamination", as for spread plate, the bacteria is more exposed to air as it is spread over the agar plate. Therefore, the result might not be accurate, as it might be contaminated. As for the pour plate method, the bacteria is in the agar itself, it is not exposed to air, thus, less risk of getting contaminated.
How many methods can scientists discover planets in other galaxies?
Scientists primarily discover planets in other galaxies through indirect methods, such as observing the dimming of light from a star when a planet passes in front of it (transit method) or analyzing the wobble of a star caused by an orbiting planet (radial velocity method). Direct imaging of exoplanets in other galaxies is more challenging due to the vast distances involved, but advancements in technology may make this possible in the future.
Advantages and disadvantages of documentary credit as compared to other methods of trade finance?
disadvantage of documentary credit payment method of international trade advantage and disavantage of advance payment method of international trade advantage and disavantage of bills of collection payment method of international trade
Advantage of Airbus A380 among other airplanes?
The main advantage is that it can ship more passengers at the same time, then other conventional passenger planes.
What are the various methods for assessing working capital requirements?
conventional method:according to the conventional method,cash inflows and outflows are matched with each other. operating cycle method:the duration of time required to complete the following sequehces of events,in case of manufacturing firms is called the operating cycle
What is the difference between the conventional method of dimensioning and the baseline method of dimensiong?
What is the difference between the conventional method of dimensioning and the baseline method of dimension
Advantage and disadvantage of the Euler method for numerical integration?
The main advantage of the Euler method is that it's one of, if not the most basic numerical method of numerically integrating ordinary differential equations. A downside however is that it can sometimes have a tendancy to be unstable unless you take stupidly small steps in the algorithm, in cases like this there are some other methods that work better.
Investment Appraisal Methods?
The Payback method is one of the investment appraisal methods. Other methods to appraise investments are the Average Rate of Return and the Net Present Value method.
What is another method other than partial sum method?
Other methods include -- QWERTY -- Rhythm -- Socratic -- IUD
What are the methods of tax planning?
Tax planning methods for small business include accounting methods and validation methods. Other methods include the accrual method and inventory valuation methods.
Do void methods have parameters?
A void method is just like any other method; it may or may not have parameters.
Do static methods operate on objects why?
No. Why? By definition. A static method is, precisely, a method that is not meant to operate on an object. It can only work with static fields, and other static methods, of its class.
What are the methods in breaking down?
Simple method is heating, other methods include to dissolve in water to react with an acid or base.
Are there any other methods for measuring resistance?
An Ohm Meter.
