optics

• What is the principle of fibre optics?

  Refractive index and total internal reflection
• What is an application of fibre optics in medicine?

  Endoscopes for internal examinations
• How are fibre optics used in communication?

  To transmit analogue and digital signals
• What happens to light when it enters a different medium?

  It changes speed and direction
• What does the refractive index (n) indicate?

  How much light slows down in a medium
• What is the refractive index of air?

  1
• What is the speed of light in a vacuum?

  Approximately $3 \times 10^8 \text{ m/s}$
• How is the normal defined in optics?

  A line perpendicular to the boundary
• What happens when light enters a higher refractive index material?

  It bends toward the normal
• What is total internal reflection?

  Light reflects back into the original medium
• What is the critical angle?

  The angle where light can no longer refract
• What is an optical fibre made from?

  Materials like silica (glass)
• What is the role of cladding in optical fibres?

  To have a lower refractive index than the core
• What are the benefits of using optical fibres in communication?

  Less signal degradation and higher capacity
• What does endoscopy refer to?

  Looking inside the body for medical reasons
• When was the first fibre optic endoscope invented?

  In 1957
• What was a limitation of early endoscopes?

  Dim red light or risk of burning
• How do endoscopes form images?

  Light reflects from internal surfaces and passes through a lens
• What is a coherent bundle in endoscopy?

  Fibres kept in the same relative positions
• How can endoscopes be used for treatment?

  By manipulating instruments through a third channel
• What are the benefits of keyhole surgery?

  Less invasive and quicker recovery
• What is a benefit of using optical fibres over copper?

  Cheaper, thinner, and lighter