Test Questions

Question 1

What is a transducer in an analytical instrument

Answer 1

Converts a chemical or physical signal/information into an electrical signal, or vice vera. Electrical signal is normally a current, voltage or charge.

Question 2

What is a data domain

Answer 2

One of the modes in which data may be encoded. Example: analog, digital, time, voltage, current, charge, frequency, period, or number

Question 3

List four input transducers and describe how they are used

Answer 3

phototube, glass electrode, electron multiplier, thermal conductivity

Question 4

What is figure of merit?

Answer 4

A number that represents a performance criterion of an instrument or method. (How valid a method is)

Question 5

What types of noise are frequency dependant? Frequency independant?

Answer 5

Frequency dependant: -flicker -environmental Frequency Indépendant: -shot -thermal/Johnston

Question 6

Name the types of noise that can be reduced by… a)Decreasing the temperature of a measurement b)increasing the frequency for the measurement c)

Answer 6

a) thermal b)environmental, 1/f noise c)thermal, shot

Question 7

Suggest a frequency range that is well suited for noise minimization. Explain.

Answer 7

10^3-10^5 Hz, and 10^6-10^7 Hz. These regions are in-between the frequencies of other things happening in the environment (AM radio, TV, etc.)

Question 8

Why is shielding vital in the design of a glass electrode that has an internal resistance of 10^6 ohms or more.

Answer 8

Because of the high impedance of a glass electrode, shielding is required to minimize induced currents from power lines and environmental noise.

Question 9

What type of noise can be reduced by… a)a high pass filter b) a low pass filter

Answer 9

a)low frequency (flicker noise) b)high frequency noise

Question 10

How to estimate signal to noise ratio from a diagram

Answer 10

1. estimate signal 2. estimate noise 3. signal to noise ratio (will have no units)