This set of Biomedical Instrumentation Multiple Choice Questions & Answers (MCQs) focuses on “Methods of Monitoring Foetal Heart Rate – 1”.
1. Which system may include lenses, mirrors, slits, diaphragm etc?
a) Radiant system
b) Optical system
c) Cardiac system
d) Photo system
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.
2. What is the most common and convenient source of light?
a) Xenon-mercury arc
b) Hydrogen discharge lamp
c) Neon-xenon arc
d) Tungsten lamp
Explanation: The most common and convenient source of light is the tungsten lamp. This lamp consists of a tungsten filament enclosed in a glass envelope. It is cheap, intense and reliable. A major portion of the energy emitted by a tungsten lamp is in the visible region and only about 15 to 20% is in the infrared region.
3. In the radiation source, for work in the ultraviolet region, a _______ is used.
a) Tungsten lamp
b) Xenon-mercury arc
c) Deuterium discharge lamp
d) Hydrogen arc
Explanation: For work in the ultraviolet region, a hydrogen or deuterium discharge lamp is used. In these lamps, the envelope material of the lamp puts a limit on the smallest wavelength which can be transmitted.
4. What are the wavelengths of quartz and fused silica respectively in a hydrogen discharge lamp?
a) 200 nm, 185 nm
b) 200 nm, 145 nm
c) 185 nm, 200 nm
d) 145 nm, 200 nm
Explanation: In these lamps, the envelope material of the lamp puts a limit on the smallest wavelength which can be transmitted. For example, quartz is suitable only up to 200 nm and fused silica up to 185 nm. The radiation from the discharge lamps is concentrated into narrow wavelength regions of emission lines. Practically, there is no emission beyond 400 nm in these lamps.
5. Modern instruments use ________ light source in calorimeters and spectrophotmetry.
a) Xenon-mercury lamp
b) Tungsten-halogen lamp
c) Mercury arc
d) Deuterium discharge lamp
Explanation: Modern instruments use a tungsten-halogen light source, which has a higher intensity output than the normal tungsten lamp in the change over the region of 320–380 nm used in colorimetry and spectrophotometry. It also has a larger life and does not suffer from the blackening of the bulb glass envelope.
6. The absorption type optical filter usually consists of coloured glasses, gelatin etc. and solutions of the coloured substances.
Explanation: The absorption type optical filter usually consists of colour media: colour glasses, coloured films (gelatin, etc.), and solutions of the coloured substances. This type of filter has a wide spectral bandwidth, which may be 40 to 50 m in width at one-half the maximum transmittance.
7. Which of the following is the dielectric?
Explanation: Interference filters usually consist of two semi-transparent layers of silver, deposited on glass by evaporation in a vacuum and separated by a layer of dielectric (ZnS or MgF2). In this arrangement, the semi-transparent layers are held very close.
8. The transmittance of interference filters varies between ________ % with a spectral bandwidth of 10 to 15 nm.
a) 15 to 20 %
b) 20 to 60 %
c) 10 to 20 %
d) 15 to 60 %
Explanation: Interference filters allow a much narrower band of wavelengths to pass and are similar to monochromators in selectivity. They are simpler and less expensive. However, as the selectivity increases, the transmittance decreases. The transmittance of these filters varies between 15 to 60 percent with a spectral bandwidth of 10 to 15 nm.
9. The expression relating the wavelength of the radiation and the angle (q) at which it is reflected is given by _________
a) ml = 2d sin q, where l= lambda
b) m = 2d sin q
c) ml = d sin q, where l= lambda
d) m = d sin q
Explanation: The expression relating the wavelength of the radiation and the angle (q) at which it is reflected is given by
ml = 2d sin q, where l= lambda.
where d is the distance separating the grooves and is known as the grating constant and m is the order of interference.
When m = 1, the spectrum is known as first order and with m = 2, the spectrum is known as second order.
10. _______ are optical systems, which provide better isolation of spectral energy than the optical filters.
Explanation: Monochromators are optical systems, which provide better isolation of spectral energy than the optical filters, and are therefore preferred where it is required to isolate narrow bands of radiant energy. Monochromators usually incorporate a small glass of quartz prism or a diffraction grating system as the dispersing media.
Sanfoundry Global Education & Learning Series – Biomedical Instrumentation.
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