How to Use a Multimeter
A multimeter is a number of meters in one. Normally a multimeter can measure voltage, current, resistance, check diodes and some can measure capacitance and check transistors. They all have a display these days normally digital, though analogue meters with a moving needle do exist. They also have a large dial, which allows the mode to be selected and also the range. The meter would be no good trying to measure 5mA current on the amp setting as it would read 0.00 A or maybe 0.01 A, either way the reading would be useless. This is why the meter has different ranges for each of its modes and it’s important to select the right one or the reading might not be accurate. Some meters are auto ranging, which means they automatically select the best range.

Measuring voltage

The voltage is measured across a component. So it would be measured by placing the black terminal on the 0v and the red terminal on the positive volts and reading the display. how_to_use_a_multimeter_1

Measuring current

Whilst a voltage is measured across a component, the current flows through the component. To take a current reading the circuit needs to be broken and the amp meter inserted. If an amp meter is placed across a circuit like it is used to take a voltage reading a massive amount of current will flow through the amp meter damaging it and potentially damaging the power source.
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The circuit in normal operation The circuit when the current reading is being taken
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