Quiz 1 Topics

Question 1

Accuracy

Answer 1

Closeness of the reading to the actual quantity being measured.

Question 2

Calibration Error

Answer 2

Type of systematic error

Can be caused by assuming a nonlinear response when in reality the response is not perfectly linear

Error in the calibration process

Question 3

Intrusive Device

Answer 3

Ex: a thermometer

Can have significant loading error due to the energy exchange between the device and the measured value

Question 4

Non intrusive Device

Answer 4

Ex: infrared sensor

Does not “intrude” on the measured value. Negligible loading error.

Question 5

Random Error

Answer 5

Caused by lack of repeatability in the output of the measuring system.

Usually caused by uncontrolled variables in the measurement process.

Question 6

Hysteresis

Answer 6

Time based dependence of the output on present and past inputs

Different output for the same input depending on if the measurement was creasing or decreasing prior to taking the reading

Question 7

Span

Answer 7

Difference between the upper and lower range limits of a measuring device

Question 8

Repeatability

Answer 8

Instruments ability to produce the same output repeatedly under the same conditions

Question 9

Sensitivity

Answer 9

Ratio of change in output over to change in input. Determined during calibration.

Ex: rise of fluid in thermometer /change in temp

Question 10

Short variable
(Length, type, range)

Answer 10

2 bytes
Integer
+/- 32000

Question 11

Long

Length, type, range

Answer 11

4 bytes
Integer
+/- 2,000,000,000

Question 12

Unsigned short
(Length, type, range)

Answer 12

2 bytes
Integer
0 to 64,000

Question 13

Unsigned long

Answer 13

4 bytes
Integer
0 to 4,000,000,000

Question 14

Float / double

Length, type, range

Answer 14

4 bytes
Floating point number
1x10^(+/-38)

Question 15

Double double

Answer 15

8 bytes
Floating point number
1x10^(+/-308)

Question 16

Short*
Int*
Double*

Answer 16

Pointer

Size depends on the OS

Question 17

Type var[#]

Answer 17

Array size = type size * #

Question 18

ISO

NIST

Answer 18

Standards organizations

Question 19

Primary standards

Answer 19

Mass, length, time, temp, current, moles, light intensity

Question 20

Secondary standards

Answer 20

Often kept in labs for calibration, they must be traceable to a primary standard (meaning they were compared to the standard at one point).

Question 21

Bias

Answer 21

A systematic error that favors a particular result

Question 22

LVDT

Linear variable differential transformer

Answer 22

1 primary coil centered between 2 secondary coils

Ferromagnetic core moves back and forth through coils, causes a voltage difference.

Coils are connected in such a way that their signs are inverted, so they will have opposite phases when the core is closer to one or the other.

Question 23

Wheatstone Bridge

Answer 23

1/4 bridge

3 resistors of the same resistance value and one strain gage. If the bridge is balanced at first, the voltage output corresponds to the change in resistance due to strain.

Question 24

Potentiometer

Answer 24

Resistance varies as a function of the position of a slider

Variable voltage divider

Inexpensive, readily available, require no signal conditioning

Question 25

Capacitive Displacement Sensors

Answer 25

Based on either the distance between the capacitor plates (non linear relationship with voltage)

Or

Change in overlapping area of the plates (linear relationship with voltage)

Question 26

Systematic Error

Answer 26

Repeatable error in a measurement that doesn’t vary with replication.

Estimated by the difference between the true value and average of many readings.