A voltage has a true value of 1.5 V analog indicating instrument with a range of 0 - 2.5 V shows a voltage 1.46 V. The relative error is :  

Concept:

Absolute error: The magnitude of the difference between the measurement of the experimental readings and the true value of the quantity is called the absolute error.

• This is denoted by |Δa |. 
• While calculating the measurements, in absence of the true value, we consider the arithmetic mean of the measurements as the true value.
• absolute error is always constant.

•  Δa = measured value - true value

Relative error: It is the ratio of mean absolute error to mean value of the quantity measured while performing the measurement.

• It is also known as fractional error.

• relative error is always expressed in percentage.
• relative error = \(\frac{Δa }{true\ value}\) × 100 
• relative error in terms of FSD(full scale deflection)= \(\frac{Δa}{FSD}\) × 100 

Calculation:

 FSD = 2.5V

true value = 1.5 V

measured value is 1.46 V

Δa = 1.46 - 1.5 = - 0.04

relative error = \( \frac {-0.04} {1.5}\) × 100

= -2.67%

so correct option is 2.