Question

zero correction in ammeter reading = ( ) amp

Answer 1

If the pointer of the ammeter is exactly at zero, when it is not connected to the circuit, then the instrument has zero error. If the pointer is above the zero mark, the the zero error is negative. The number of divisions it is above the zero mark are to be subtracted from the reading.

Answer 2

HEY BUDDY HERE IS UR ANSWER !!

Generally for a standard (Not Clamp-on) Ammeter or Voltmeter, short the terminals and read the meter. Any reading other than zero is the Zero error.

Also, for mechanical movements, ensure that the meter face is fully discharged of static electricity by wiping it down gently with a damp cloth with a bit of detergent like Dawn in it to dissipate any charge. This is because the needle is very low mass, balanced delicately and will respond to electrostatic fields easily causing erroneous readings . Plastic face meters in a low humidity environment are particularly susceptible to this effect.

Stray magnetic fields (including the earths) can also disturb the zero setting on mechanical and digital (due to AC induction) meters. Changing their orientation 90 degrees in each of the three axis of movement and repeating the tests can assist in characterizing this and also any gravitational effects on mechanical units.

Analog (Mechanical) meter movements usually have a screw on the front that allows for Zeroing the movement. Make certain that you correct for parallax by viewing the needle and tic marks exactly perpendicular to the needle and face. (Anti-parallax mirrors are provided on many better movements. Adjust your viewing angle so that you cannot see the reflection of the needle in the mirror). Set it for zero by gently turning the screw small fractions of a turn. The screw is designed to be only effective for about 1/2 of a turn and turning it farther may damage the movement.

Correcting digital (Including clamp-on) meters is an entirely different matter and will usually require the manufactures calibration instructions to actually calibrate them. However you can use the techniques above to get a correction value to add to or subtract from your readings.

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