Question

the systematic errors of an instrument can be reduced by making: a. the sensitivity of instrument to environmental input as low as possible b. systematic errors does not depend on the sensitivity of instrument c. none of the mentioned d. the sensitivity of instrument to environmental input as high as possible

Answer 1

Random errors in experimental measurements are caused by unknown and unpredictable changes in the experiment. These changes may occur in the measuring instruments or in the environmental conditions.

Examples of causes of random errors are:

electronic noise in the circuit of an electrical instrument,

irregular changes in the heat loss rate from a solar collector due to changes in the wind.

Random errors often have a Gaussian normal distribution (see Fig. 2). In such cases statistical methods may be used to analyze the data. The mean m of a number of measurements of the same quantity is the best estimate of that quantity, and the standard deviation s of the measurements shows the accuracy of the estimate. The standard error of the estimate m is s/sqrt(n), where n is the number of measurements.

Fig. 2.

Fig. 2. The Gaussian normal distribution. m = mean of measurements. s = standard deviation of measurements. 68% of the measurements lie in the interval m - s < x < m + s; 95% lie within m - 2s < x < m + 2s; and 99.7% lie within m - 3s < x < m + 3s.

The precision of a measurement is how close a number of measurements of the same quantity agree with each other. The precision is limited by the random errors. It may usually be determined by repeating the measurements.

Answer 2

The systematic errors of an instrument can be reduced by making:

a. the sensitivity of instrument to environmental input as low as possible

b. systematic errors does not depend on the sensitivity of instrument

c. none of the mentioned

d. the sensitivity of instrument to environmental input as high as possible

Explanation:

• Systematic errors are caused by imperfect calibration of measurement instruments or imperfect methods of observation or interference of the environment with the measurement process.
• In order to increase the efficiency the sensitivity of instrument to the environment should be as low as possible.

Hence, the correct option is (a) i.e.the sensitivity of instrument to environmental input as low as possible.