Answer: (b) temperature and torsional effects are automatically compensated for by the bridge,
Explanation:
As can be seen, strain gages 1 and 4 are on top of the beam and strain gages 2 and 3 are on the bottom of
the beam. Therefore strain gages 1 and 4 experience a tensile strain (are stretched) and strain gages 2
and 3 experience a compressive strain. If the relationship between strain and resistance is linear, then
under some load F the changes in resistance will be
R1= R1 + dR1
R4= R4 + dR4
tensile(4)and
R ¢2= R2 -dR2
R ¢3= R3 -dR3
compressive. (5)
when the four strain gages have an equal nominal
resistance (i.e., R1 = R2 = R3 = R4 = R) then the deflection method Wheatstone bridge equation reduces to the linear equation
Using known weights, a calibration curve can be established that relates the weight W to the output
voltage on a digital meter Eo,
Eo= a0 + a1W , (4)
where a0 and a1 are some constants. Once an unknown weight is known, an unknown mass or density
