An analog computer works on continuously changeable aspects of physical phenomenon such as fluid pressure, mechanical motion and electrical quantities. These computers measure changes in continuous physical quantities say current and voltage. These computers are used to process data generated by ongoing physical processes. A thermometer is an example of an analog computer since it measures the change in mercury level continuously. Although the accuracy of an analog computer is less as compared to digital computers, yet it is used to process data generated by changing physical quantities especially when the response to change is fast. Most present day analog computers are well suited to simulating systems. A simulator helps to conduct experiments repeatedly in real time environment. Some of the common examples are simulations in aircrafts, nuclear power plants, hydraulic and electronic networks.