potentiometer level measurement

A potentiometer is a device to measure potential difference across a conductor on the basis of null point. Principle of Potentiometer: It's based on Ohm's law i.e. V=IR V= I rho l/A [ R= rho l/A]V is directly proportional to l, when I, rho & A are costantSo, V= Kl [K is constant of P.meter] P.meter doesn't draw any current from the cell when zero deflection is observed as such it is more accurate than a voltmeter.It is used to measure internal resistance also , potential difference between two points, emf. V.meter:Its working is based on deflection method, it always draws some current from the circuit, so it measures less than actual potential. It is use to measure potential difference only.

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A potentiometer is a manually adjustable resistor. The way this device works is relatively simple. One terminal of the potentiometer is connected to a power source. Another is hooked up to ground (a point with no voltage or resistance and which serves as a neutral reference point), while the third terminal runs across a strip of resistive material. This resistive strip generally has a low resistance at one end; its resistance gradually increases to a maximum resistance at the other end. The third terminal serves as the connection between the power source and ground, and is usually interfaced to the user by means of a knob or lever. The user can adjust the position of the third terminal along the resistive strip in order to manually increase or decrease resistance. By controlling resistance, a potentiometer can determine how much current flows through a circuit. When used to regulate current, the potentiometer is limited by the maximum resistivity of the strip. The power of this simple device is not to be underestimated. In most analog devices, a potentiometer is what establishes the levels of output. In a loud speaker, for example, a potentiometer directly adjusts volume; in a television monitor, it controls brightness.

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