Question

A single strain gage has a nominal resistance of 120 ohm. For a quarter bridge with 120 ohm fixed resistors, strain gauge factor is 2.01 with a strain of 1000-μstrain for a supply voltage of 3V. Compute the Voltage output as mV?

Answer 1

Output voltage is 1.507 mV

Solution:

As per the question:

Nominal resistance, R =
`120\Omega`

Fixed resistance, R =
`120\Omega`

Gauge Factor, G.F = 2.01

Supply Voltage,
`V_(s) = 3\ V`

Strain,
`\epsilon = 1000* 10^(-6)\ strain`

Now,

To calculate the output voltage,
`V_(o)`:

WE know that strain is given by:

`\epsilon = ((R + R')^(2)V_(o))/(RR'V_(s)* G.F)`

Thus

`V_(o) = (RR'V_(s)\epsilon * G.F)/((R + R')^(2))`

Now, substituting the suitable values in the above eqn:

`V_(o) = (120* 120* 3* 1000* 10^(-6)* 2.01)/((120 + 120)^(2))`

`V_(o) = 1.507\ mV`