Light

• 1st law of reflection: The incident Ray, reflected Ray, and the normal at the point of reflection lie in the same place.
• 2nd law of reflection: The angle of incidence, is equal to the angle of reflection.
• Characteristics of a plane mirror:

  • Laterally inverted
  • Image is the same size as the object
  • Upright
  • Virtual
  • Image and object are equally far from the mirror.
• Light travels faster in an optically less dense medium. (Eg: )
• Light travels slower in an optically denser medium. (Eg: glass)
• Refractive index of a medium is the ratio of the speed of light in a vacuum to the speed of light in a medium.
• The light rays coverge together after passing through a convex len.
• Focal length is the distance between the optical centre and the focal point.
• Potential difference is the work done per unit charge.
• Unlike charges attract (attractive electric forces), like charges repel.
• Electric current is the rate of flow of electric charge.
• Resistance of a component is the ratio of the potential difference across it to the current flowing through it.