Electricity, Waves, Optics and Ultrasound
Electrical principles and safety, waves, sound, Doppler, ultrasound imaging, light and optical instruments.
How to prepare for the current Primary FRCA MCQ
Build mechanisms first, practise calculations with units, connect equipment to failure modes and finish every SBA by choosing the single best answer to the exact lead-in.
Core concepts
Concept 1
Voltage, current, resistance, capacitance, impedance and power describe electrical circuits and patient-safety hazards.
Exam cue: Draw the circuit or wave path before choosing an equation.
Concept 2
Reflection, refraction, absorption, scattering, attenuation and Doppler shift determine optical and ultrasound behaviour.
Exam cue: Name the energy form, medium, interface and detector before predicting a signal.
Risk pitfalls and guardrails
Applying a direct-current resistance model without considering impedance or frequency.
Guardrail: Do not choose an option merely because it states a true fact; choose the one that best answers the exact lead-in under the stated conditions.
Confusing ultrasound frequency, intensity and propagation speed.
Guardrail: Do not choose an option merely because it states a true fact; choose the one that best answers the exact lead-in under the stated conditions.
Memory anchors
What is Ohm's law?
Potential difference equals current multiplied by resistance for an ohmic conductor under the stated conditions.
How is electrical power related to voltage and current?
Power equals voltage multiplied by current.
What determines ultrasound reflection?
The difference in acoustic impedance across an interface and the angle of incidence.
What is the Doppler principle?
Detected frequency changes when source, reflector and receiver move relative to one another.
What is the ultrasound frequency trade-off?
Higher frequency improves resolution but attenuates more, reducing penetration.
Checkpoint rule
Do the check-up only after you can summarize each concept in one sentence and identify one dangerous pitfall from memory.
Knowledge Check (after reading)
Short check-up to confirm understanding of this module.
Check-up Questions
Ohm's law relates voltage to which product?
A 12 V source drives current through a 6 Ω resistor. What current flows?
Answer all questions to submit.
Next step personalized recommendations
Continue learning
Move forward only after this module is stable.
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