How does the meter have to connect to the battery in order to provide an indication?

Answer 1

The meter ( as refered to a conventional moving coil analog pointer type ) basically operates on a Direct Current ( DC ) passing in its coils. Hence the meter inherently has a polarity of operation i.e the positive & negative inputs of the meter must be connected appropriately with the corresponding positive & negative potentials in the circuit being measured , so that the meter deflection is in the correct direction of the measuring scale ( typically clockwise movement )

Bsis Voltage & current measurement scales are linear , while resistance ohmic measurement scales are generally non linear.

Incorrect polarity of connection will result in the meter deflecting in the opposite direction & usually will not damage the meter unless an inappropriate measuring range was selected.

Whenever the magnitude of measured voltage or current is not known approximately beforehand, the best precaution is to use the highest range on the meter & stepping down the range if the deflection is too low for a good reading.This will prevent damage to the meter due to overload deflection which generally will damgage the delicate moving parts of the meter, which results in a total writeoff.

For measuring voltages , the meter configuration as a voltmeter is used, where a series voltage dropping high value resistor appropriate to the range of voltage being measured is incorporated into the meter itself. The voltmeter is always connected across the points where the measurement is required. Hence no alteration of circuit is required for this measurement.

For measuirng current, a low value resistor across the coils of the meter is incorporated appropriate to the range value of currents being measured, as a shunt to divert currents larger than what the basic meter can handle. It is necessary to break the circuit at a convinient point where the measurement is required and the meter inserted into the circuit. Hence an alteration of circuit is required for this measurement.

When a meter is configured to measure resistance , a low voltage battery source with appropriate circuitry is incorporated into the meter itself to read the resistance value directly in ohms.

Modern digital meters generally have bipolar measurement capabilities, in which the polarity of measurement is indicated. Here only the moving coil meter is replaced by a analog to digital convertor chip which directly displays the value on the digital readout. Otherwise the same measurement principles apply.