Resistance strain gauge

Resistance strain gauge is a device that experiences a change in resistance when they are stretched or strained. They are able to detect very small displacements, usually in the range 0–50µm, and are typically used as part of other transducers.

Photocells in Measurements

Photocells are sensors that allow you to detect light and hence detect the motion. A Photocell is basically a resistor that changes its resistive value (in ohms) depending on how much light is shining. A photocell consists of a semi cylindrical photo sensitive metal plate (emitter) and a

LVDT (Linear Variable Differential Transformer)

The linear variable differential transformer (LVDT) is used to measure the translational displacement of the object which is in physical contact with it.

Wire wound potentiometer

Wire wound potentiometer comprises of several rounds of wire wound around the shaft of the non-conducting material. The turns of the coil are bonded together by an adhesive. In this case the slider, connected to the body whose

Accuracy and Precision in Measurements

The Accuracy of a measurement system is defined as the degree of closeness of measurements of a quantity to that quantity’s actual (true) value. The precision of a measurement system, also called

Sources of errors in Measurements

1. Instrument calibration
Due to frequent use of a measuring instrument and also of aging, the instrument may go out of calibration. The measurements made with such an instrument will be in error; this type of error usually is regular and may be called systematic. A comparison with a

Errors and Types of Errors in Measurements

Errors
Error is the difference between the measured value and the true value of a measurement. It is the deviation from the expected perfection. Any measurement, however carefully it is conducted, is subject to measurement errors. These errors make it difficult to

Dynamic Performance of Characteristics

The dynamic behavior of an instrument can be determined by applying some form of known arid predetermined input to its primary element and then study the output, i.e. movement of the pointer. Generally the behavior is judged for three types of inputs:

Static Performance of Characteristics

A set of criteria that provide meaningful description of quality of measurements under static conditions are called static characteristics. These criteria are

1. Accuracy
Accuracy is defined as the closeness with which the reading of the instrument approaches true value. The true value is just impossible to be determined experimentally. True value of a quantity can be defined as

Block Diagram of a Generalized Description of a Measurement Instrumentation

1. Measured medium

2. Measured quantity 

3. Primary sensing element

4. Variable conversion element

Basic Concepts of Measurements

Measurement of a quantity is the act or result of a quantitative comparison between a predefined standard and an unknown magnitude. The act of measurement must satisfy,
a) The standard must be accurately known and internationally accepted.
b) The apparatus and the experimental procedure adopted for comparison must be provable.
The standard of length is the standard meter defined as a