Olympiad Test: Light

The phenomenon of splitting of white light into seven colours is called dispersion of light.

Virtual image is always erect and magnified or diminished and behind the mirror.

Concave lens always forms virtual and erect image smaller in size.

Light travels faster in rarer medium than denser medium. So, light travels fastest in air.

Red colour of light have longer wavelength than blue, green and orange and is scatter least.

White light consists of 7 colours which can be visualised when white light passes through a prism.

Band of seven colours of light appeared on screen when white light passes through a prism is called spectrum.

Real image always inverted. Real image can be obtained on screen.

In a concave mirror the reflecting surface is bent towards inward.

Plane mirror always form image that is virtual, erect and of same size of object.

Beam is collection of rays originating from a source of light.

All the rays of light parallel to principle axis after reflection pass through focus of the mirror or lens.

Sky appears red during sunrise and sunset because rays of light travel longer distance during sun rise and sunset to scatter other colour light.

Convex mirrors have a very wide field of view as they are curved outwards. So, the convex mirrors enable the driver to view a much larger area than a plane mirror. The images produced are erect and their size is much smaller than the object. Hence, it is used as a rear view mirror in automobiles to see objects at the backside of the vehicle.

Rainbow is formed due to dispersion of light through tiny water droplets present in atmosphere just after the rain.

Reading glass is a transparent object as light can easily pass through it.

In convex mirror, the reflection of light takes place at bulging out surface of the mirror.

A diverging mirror is convex mirror that always form virtual, erect and diminished image of object.

In regular reflection, angle of incidence is always equal to angle of reflection.