Author name: Abhay Krishnan

A light dependent resistor(LDR) is used to detect the presence or level of light. They work on the basic principle of photo-conductivity. It is also called a photoresistor, photoconductor or photocell. The circuit symbol of an LDR is shown in the figure. LDR consist of a resistor made up of semiconductor material. Cadmium sulphide and […]

Radiation is the emission of energy from matter in the form of rays or high-speed particles. Broadly, it can be thought of as either electromagnetic radiation (like radio waves or visible light) or particle radiation (like alpha particles or beta particles). Radiation Sensors or Radiation Detectors are devices that can sense and measure radiation. The

Electromagnetic flow meters are suitable for measuring the flow of electrically conducting liquid. Schematic diagram of an electromagnetic flowmeter is shown in the figure. It consists of a pair of electrodes fixed in the opposite sides of a pipe carrying the fluid whose flow is to be measured. A pipe with non-conducting and non-magnetic property

A hot wire anemometer is a temperature transducer used for measuring flow rate. When the electrically heated temperature sensor is placed in a flowing fluid, heat is transferred from the sensor to the fluid. Hence the temperature of the sensor reduces resulting in a change in resistance of the wire. The amount of cooling of

Flow meters are the devices used for measuring the flow rate of liquids or gases. Flow rate can be defined as the volume of fluid flowing through an area in unit time. In a pipe, the flow rate can be expressed in terms of speed of the fluid and the cross-sectional area of the pipe.

Flow meters are the devices used for measuring the flow rate of liquids or gases. They work on Bernoulli’s principle and continuity equation. The Continuity equation The continuity equation represents that the product of the cross-sectional area of the pipe and the velocity of the fluid at any point is always a constant. Consider the

A level transducer is a device that produces an electric signal with respect to a liquid level. Level transducers are classified based on following measurement methods Direct and indirect level measurements. Continuous and discrete level measurements. In direct method of measurement, the liquid level is converted directly to electrical signal. This can be done with

A pressure transducer is a device that converts pressure into an analog electrical signal. Measuring Pressure Pressure is measured in three forms. Absolute pressure is a pressure that is relative to the zero pressure in a vacuum. Gage pressure is the pressure relative to atmospheric pressure. Differential pressure is the difference in pressure at two

When the temperatures being measured are very high, it is impossible to have physical contact with the medium to be measured. Temperature sensors that work on radiation methods and hence require no physical contact with the radiating system are called Radiation Pyrometers. Construction of Radiation Pyrometer The radiation pyrometer have three basic components The optical

A thermocouple is an active transducer that measures temperature. It works on the principle of see back effect. They are extensively used for temperature measurement in industrial applications. Thermocouple Construction and Types A thermocouple consists of two different types of metals joined together at one end (hot junction) and terminated at another end (cold junction).