Free help with homework

Why join Brainly?

  • ask questions about your assignment
  • get answers with explanations
  • find similar questions


Mirrors, spherical or otherwise, operate on the principle that the angle of reflection of a ray of light equals the angle at which it strikes the mirror's surface. That behavior is not affected by the medium in which the light travels, so the mirror's focal length would be no different in air or water.

If you had asked about the focal length of a LENS, however, the answer would be different. Lenses work by REFRACTION, not reflection, and the angle of refraction is based on the difference between the speed of light in the lens compared to the surrounding medium. When immersed in water, the difference between light's speed in the lens and the surrounding medium is less than the difference when it's in air, and the focal length of a lens would be greater under water. 

2 5 2
It changes

the focal length will be more in water for a mirror
2 5 2
The Brain
  • The Brain
  • Helper
Not sure about the answer?
Learn more with Brainly!
Having trouble with your homework?
Get free help!
  • 80% of questions are answered in under 10 minutes
  • Answers come with explanations, so that you can learn
  • Answer quality is ensured by our experts