Ammeter Ammeter is an electrical measuring device, which is used to measure electric current through the circuit.CONNECTION OF AMMETER IN CIRCUITAn ammeter is always connected in series to a circuit.SYMBOL

Ammeter Ammeter is a low resistance galvanometerIt is used to measure the current in a circuit in amperesGalvanometer can be converted into an ammeter by using a low resistance wire in parallel with the galvanometer the resistance of the wire depends upon the range of the ammeter As shunt resistance is small the combined resistance of the galvanometer & the shunt is very low hence the ammeter has much lower resistance than galvanometerAn ideal ammeter has zero resistance

Voltmeter Voltmeter is an electrical measuring device, which is used to measure potential difference between two points in a circuit. CONNECTION OF VOLTMETER IN CIRCUITVoltmeter is always connected in parallel to a circuit. SYMBOL 

Voltmeter Volt meter is a high resistance galvanometerIt is used to measure the potential difference between two points of a circuit in voltsA galvanometer can be converted into a volt meter by using a high resistance in series with the galvanometerThe value of resistance depends upon the range of the volt meterFor voltmeter a high resistance, R is connected in series with the galvanometer therefore resistance of voltmeter is very large as compared to that of galvanometerThe resistance of an ideal voltmeter is infinity

http://www.hiwtc.com/photo/products/26/00/15/1507.jpg

Ohmmeter The purpose of an ohmmeter, is to measure the resistance placed between its leads. This resistance reading is indicated through a mechanical meter movement which operates on electric current.The ohmmeter must then have an internal source of voltage to create the necessary current to operate the movementAlso have appropriate ranging resistors to allow just the right amount of current through the movement at any given resistance

Simple ohmmeter circuit

A multimeter is a device used to measure electrical current, voltage, and resistance.A multimeter combines several electrical meters into one handheld unit. Basic multimeter models can measure voltage, current and resistance. Advanced models can also measure temperature, inductance, capacitance, duty cycle and frequency. They can also test diodes and transistors. Some even work as an oscilloscope. The two main types of multimeter are digital and analogue

Multimeter

Thank You..