Properties of light- Part 1

Light optics:

Light has dual property ie. It can behave as both wave and ray.

Light travels in a straight line. Light may deviate in its path only when it hits or passes through another medium.

Ray optics does not provide information about characteristics like intensity and colour. 

The path of the light is called ray, and a bundle of such rays is called a beam of light.

While using a plane mirror, we can learn two types of image formation.

Real image and Virtual image formation.

Real image:

Condition needed: Rays actually converge at the image.

This image can be formed on a screen as it is in front of the mirror.

Can also be seen with the eyes.

Virtual image:

Condition needed: Rays appear to diverge from the image.

This image cannot be formed on a screen as the image is behind the mirror.  

Can only be seen with the eyes.

Reflection, Refraction and Critical angle: Self-explanatory.

Total Internal Reflection

If the angle of incidence in a denser medium is increased beyond the critical angle, there is no refraction possible into rarer medium. The whole light gets reflected back into the denser medium itself and the phenomenon is called total internal reflection.

Conditions necessary:

ii) Light must travel from a denser to rarer medium.

ii) Angle of incidence in denser medium must be greater than critical angle.

Practical applications:

• Glittering of diamond
• Mirage and looming
• Prisms making using of total internal reflection
• Radius of illumination (Snell’s window)
• Optical fiber