Physics viva
1. You are shown a card on which a variety of electrical symbols are displayed; identify as many symbols as possible.
2. Where is the capacitor symbol commonly used?
3. You are shown two charts representing defibrillator circuits; answer the following questions:
- What are charging and discharging circuits?
- Discuss the various components in the circuit.
- What is an inductor?
- Why is an inductor used in defibrillator circuits?
- What is the current intensity and duration in the defibrillator?
- What type of waveform is shown?
- Describe the charging of a capacitor, in basic physical terms.
- What is the effect of alternating current and direct current across a capacitor?
- How do you convert an AC to a DC current?
4. You are presented with a photograph showing various types of endotracheal tubes.
- Identify these endotracheal tubes.
- What is the main difference between paediatric and adult tubes?
- Why are uncuffed tubes used in paediatrics?
- What is the narrowest part of the larynx in the adult?
- What is the difference between the two cuffs?
- Draw the two cuffs and explain their respective features in detail.
- What are the advantages and disadvantages of these two cuffs?
- What is the range of cuff pressures that is used, and why is this the case?
- For a given flow, in which type of tube is the flow likely to be turbulent?
- What is Reynold’s number, and what formula is associated with it?
- What is critical flow?
5. You are shown a chart containing the absorption characteristics of oxyhaemoglobin and deoxyhaemoglobin.
- Explain the various features of these curves, and indicate the isosbestic points.
- What wavelengths are used?
- Why are there two wavelengths?
- Which wavelength is that of red and which infrared?
- How does a pulse oximeter differentiate between pulsatile and non-pulsatile components?
- What are the laws behind the principle of the pulse oximeter?
- Explain these laws
- What is the difference between a pulse oximeter and a bench oximeter?
- What sources of errors can occur while using a pulse oximeter?
ArticleDate:20050628
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