Optical Fibres
4 marks · NormalRead the passage: 'A bundle of optical fibres is used in a medical endoscope to allow a doctor to see inside a patient’s stomach.'
Describe how the endoscope uses optical fibres to allow the doctor to see inside the body.
State two reasons why using an endoscope made with optical fibres is an advantage for the patient, compared to traditional open surgery.
Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.
Show answer
(a) Light travels down one bundle to illuminate; light reflected from inside travels back up another bundle, forming image. · must show illumination and image formation
(b) Smaller cuts/keyhole surgery; less pain; less risk; faster recovery. · must show patient-centered benefits
Must show: light travels down one bundle; image returns up second bundle; less invasive; faster recovery
Common mistakes: Not mentioning two bundles; giving technical/doctor advantages, not patient.
Show mark scheme and worked solution
Marking points
M1 (a) · 1 mark · Describes light travelling down one bundle to illuminate the region being examined.
M1 (a) · 1 mark · Describes light/image returning up a second bundle to the eyepiece.
B1 (b) · 1 mark · States one appropriate advantage for the patient (smaller cut, less pain).
B1 (b) · 1 mark · States a second advantage for the patient (faster recovery, less risk of infection, etc.).
Worked solution
a) In an endoscope, light travels down one bundle of optical fibres to illuminate the area being viewed. The reflected light from the inside of the stomach travels up a second bundle of fibres, forming an image at the eyepiece. b) The use of optical fibres enables smaller incisions (keyhole surgery), which means less pain and a faster recovery for the patient.