Ultrasound and Doppler
Wavelength is the distance between two points of maximum compression or rarefaction. The frequency of a wave is the number of wavelengths per second expressed as hertz (Hz). High-frequency sounds…
Surface tension
Surface tension is commonly measured as force per unit length or energy per unit area. The curved meniscus formed in column of mercury in the liquid barometer is an example…
Cleaning, disinfection and sterilisation
html xmlns=”http://www.w3.org/1999/xhtml” xmlns:mml=”http://www.w3.org/1998/Math/MathML” xmlns:epub=”http://www.idpf.org/2007/ops”> Chapter 38 Cleaning, disinfection and sterilisation Basic science Cleaning is the physical removal of contaminants from an object by mechanical or manual action such as washing….
Wheatstone bridge and strain gauges
The typical Wheatstone bridge arrangement as shown above contains a power source, a galvanometer (G), two resistors of known resistance (R1, R2), a variable resistor (R4) and an unknown resistance,…
Gas analysis
Photo-acoustic spectrometry has a higher accuracy, better reliability and does not need as frequent calibration compared to infrared absorption spectrometry. What are the common causes of error with infrared analysers?…
Light and optical fibres
html xmlns=”http://www.w3.org/1999/xhtml” xmlns:mml=”http://www.w3.org/1998/Math/MathML” xmlns:epub=”http://www.idpf.org/2007/ops”> Chapter 29 Light and optical fibres Basic science Light is the part of the electromagnetic spectrum that is visible to the human eye. It has wavelengths…
Electricity – generation and distribution
Three-phase power leaves the power station via three wires (one for each phase of AC) to enter a step-up substation. Here, transformers convert the power station output to a very…
EEG and EMG
Applied science How are the EEG and EMG used in anaesthesia? Performing a complete EEG with 20–22 electrodes in the intraoperative environment is not practical and the raw EEG is…
