Question 1
Which of the following component is used for selection of narrow band in spectrophotometer?
A. Optical system
B. Radiating source
C. Filtering Arrangement
D. Detecting system
View Answer
Answer: C
Explanation: A source of radiant energy, which may he a tungsten lamp, a xenon-mercury arc, hydrogen or deuterium discharge lamp, etc. Filtering arrangement for the selection of a narrow band of radiant energy. It could be a single wavelength absorption filter, an interference filter, a prism or a diffraction grating.
Question 2
What is used for the measurement of unabsorbed radiant energy in spectrophotometer?
A. Optical system
B. Radiating source
C. Filtering Arrangement
D. Detecting system
View Answer
Answer: D
Explanation: An optical system for producing a parallel beam of filtered light for passage through an absorption cell (cuvette). The system may include lenses, mirrors, slits, diaphragm, etc. A detecting system for the measurement of unabsorbed radiant energy, which could be the human eye, a barrier-layer cell, phototube or photo-multiplier tube.
Question 3
Which of the following method uses only the human eye as a measuring instrument?
A. Telemetric
B. Colorimetric
C. Polarimetric
D. Calorimetric
View Answer
Answer: B
Explanation: A colorimetric method in its simplest form uses only the human eye as a measuring instrument. This involves the comparison by visual means of the colour of an unknown solution, with the colour produced by a single standard or a series of standards. The comparison is made by obtaining a match between the colour of the unknown and that of a particular standard by comparison with a series of standards prepared in a similar manner, as the unknown.
Question 4
Which of the following detector is required in spectrophotometer?
A. Phototransistor
B. Photodiode
C. LDR
D. Photomultiplier
View Answer
Answer: D
Explanation: The amount of light reaching the detector of a spectrophotometer is generally much smaller than that available for a colorimeter, because of the small spectral bandwidth. Therefore, a more sensitive detector is required. A photomultiplier or vacuum photocell is generally employed.
Question 5
The recorder used with spectrophotometers has _____ wavelength scanning speeds.
A. one
B. two
C. three
D. four
View Answer
Answer: D
Explanation: The recorder used with spectrophotometers have four wavelength scanning speeds (100, 50, 20 and 5 nm/mm) and seven chart speeds (10, 5, 2, 1, 0.5, 0.2 and 0.1 inch/mm). It has a sensitivity of 100 mV absorbance units or 100 mV/100% T.
Question 6
The recorder used in spectrophotometers has ______ chart speeds.
A. three
B. five
C. seven
D. nine
View Answer
Question 7
Which component is used in spectrophotometer for control, Signal Processing, and Communication functions?
A. Detector
B. Microprocessor
C. Deuterium Lamp
D. Tungsten Lamp
View Answer
Answer: B
Explanation: A microprocessor, in a spectrophotometer, could be used for the following functions: Control functions: Wavelength scanning, automatic light source selection, control of slit width, detector sensitivity, etc. Signal processing functions: Baseline correction, signal smoothing, calculation of % T, absorbance and concentration, derivative, etc. Communication functions: Keyboard entry, menu-driven operations, data presentation, warning display, communication with external systems, etc.
Question 8
Which of the following component is used to produce a parallel beam of filtered light for passage through an absorption cell(cuvette) in spectrophotometer?
A. Optical system
B. Radiating source
C. Filtering Arrangement
D. Detecting system
View Answer
Answer: A
Explanation: An optical system for producing a parallel beam of filtered light for passage through an absorption cell (cuvette). The system may include lenses, mirrors, slits, diaphragm, etc. A detecting system for the measurement of unabsorbed radiant energy, which could be the human eye, a barrier-layer cell, phototube or photo-multiplier tube.
Question 9
Which of the following instrument isolates monochromatic radiation in a more efficient and versatile manner than colour filters in filter photometers?
A. Calorimeter
B. Colorimeter
C. Spectrophotometer
D. Polarimeter
View Answer
Answer: C
Explanation: A spectrophotometer is an instrument which isolates monochromatic radiation in a more efficient and versatile manner than colour filters used in filter photometers. In these instruments, light from the source is made into a parallel beam and passed to a prism or diffraction grating, where light of different wavelengths is dispersed at different angles.
Question 10
Spectrophotometer generally employs a 6V Xenon Arc Lamp, which emits radiation in a wavelength region of visible light.
A. True
B. False
View Answer
Answer: B
Explanation: False, Spectrophotometers generally employ a 6 V tungsten lamp, which emits radiation in the wavelength region of visible light. Typically, it is 32 candle power. These lamps should preferably be operated at a potential of say 5.4 V when its useful life is estimated at 1200 h.