Construction and principle of operation of moving coil- moving iron- Dynamometer-D-C- and A-C- potentiometers- Electrostatic instruments- measurement of inductances- capacitance and frequency by A-C- Bridges -Thermal and Rectifier type deflecting instruments- Deflecting- controlling and damping torques- Measurement of power in polyphase circuits- C-R-O- construction & principle measurement of voltage- current- frequency and phase by oscilloscope- Electronic voltmeters – analog and digital- Digital multimeters- Audio oscillators- signal generators and frequency counter. Data Acquisition Systems, PC Based Measuring Systems, Performance Characteristics of Sensors and Actuator, Optical sensors, Temperature Sensors, Magnetic and Electromagnetic Sensors and Actuators, Mechanical Sensors, Acoustic Sensors and Actuators, Chemical Sensor, Radiation Sensors.Transducers: Introduction,