Compare primary and secondary instruments.

1 Answer

Answer :

Primary instruments 
Secondary instruments 
Gives magnitude of quantity in terms of physical constants of instrument 
Gives reading directly of the quantity measured. 
Need no calibration 
Calibrated with respect to absolute instruments 
Measurement is tedious and time consuming (as indirect) due to calculations needed to be done 
Quick method as direct method of reading.
Very rarely used. 
Very widely used.
e.g. tangent galvanometer and current balance galvanometer. 
e.g. magnetic meter, induction meter, hotwire meter and electrostatic meter 

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