AC and DC meters

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

Ammeter Ammeter is a low resistance galvanometer It is used to measure the current in a circuit in amperes Galvanometer 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 galvanometer An 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 CIRCUIT Voltmeter is always connected in parallel to a circuit. SYMBOL  

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

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 movement Also have appropriate ranging resistors to allow just the right amount of current through the movement at any given resistance

Simple ohmmeter circuit

Multimeter 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

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