Science Light – Reflection and Refraction Notes

Laws of Reflection

  1. Angle of incidence = Angle of reflection.

  2. Incident ray, normal, and reflected ray are coplanar.

Mirror Formula and Magnification

  • Mirror Formula:
    1f=1v+1u\frac{1}{f} = \frac{1}{v} + \frac{1}{u}
    Where:

    • f = focal length

    • v = image distance

    • u = object distance

  • Magnification (m):
    m=h′h=−vum = \frac{h'}{h} = -\frac{v}{u}
    Where:

    • h' = image height

    • h = object height

    • Positive magnification = virtual image

    • Negative magnification = real image

Sign Convention for Reflection

  • New Cartesian Sign Convention:

    • Origin at the pole (P) of the mirror.

    • Objects are placed to the left; distances to the right are positive.

    • Distances above the principal axis are