Science 5 Marks Questions

White light appears colourless, but it is actually a mixture of seven different colours. These seven colours are Violet, Indigo, Blue, Green, Yellow, Orange, and Red, commonly remembered as VIBGYOR.
1.When a beam of white light is passed through a glass prism, it splits into seven colours.
2.This phenomenon is called dispersion of light.
3.The splitting occurs because different colours of light have different wavelengths.
4.Due to different wavelengths, each colour refracts by a different angle inside the prism.
5.Violet light bends the most, while red light bends the least, forming a spectrum.
6.The band of seven colours formed on a screen is called the spectrum of white light.
7.A rainbow is a natural example of dispersion, where sunlight splits into seven colours due to water droplets in the atmosphere.

Converging nature-
A mirror or lens is said to have a converging nature if it brings parallel rays of light together at a single point after reflection or refraction.
The point at which the rays meet is called the focus.
Concave mirrors and convex lenses show converging nature.
Due to convergence, these optical devices can form real and inverted images.
Example: A convex lens converges sunlight to a bright spot.
Diverging nature
A mirror or lens is said to have a diverging nature if it spreads out parallel rays of light after reflection or refraction.
The rays appear to come from a point called the virtual focus.
Convex mirrors and concave lenses show diverging nature.
Due to divergence, these devices generally form virtual and erect images.
Example: A concave lens spreads light rays outward.

(i) Uses of a plane mirror:
Plane mirrors are used as looking mirrors in homes and shops.They are used in periscopes and other optical devices.
(ii) Uses of a convex mirror:
Convex mirrors are used as rear-view mirrors in vehicles.They are used as security mirrors in shops and parking areas.
(iii) Uses of a concave mirror:
Concave mirrors are used as shaving or make-up mirrors to see a magnified image.They are used as reflectors in headlights and torches.
(iv) Uses of a concave lens:
Concave lenses are used in spectacles to correct short-sightedness (myopia).
They are used in door viewers (peepholes).
(v) Uses of a convex lens:
Convex lenses are used in magnifying glasses.They are used in cameras, microscopes, and projectors.