As the sun is relatively low in the sky during sunrise or sunset, the rays of the sun strike the window and reach our eyes, which are at a similar height to the window. At midday, the sun is very high, so rays from the sun that strike the window reflect downward and so we are not able to see the reflection.
It is much easier to read from rough pages as they undergo diffused reflection. Glossy pages result in regular reflection and cause a glare on our eyes. The reader mostly sees an image of the light source which illuminates the page, rather than seeing the text and pictures on the page.
We see objects only when light reflected by that object reaches our eyes. In a dark room, there is no light that can be reflected by any object and so we are unable to see objects. But if there is light outside the room, we can see those objects, since they will reflect light that will reach our eyes.
A ray of light falling normally on a mirror means that it is falling on the mirror at
to the mirror surface. Therefore, the incident ray and the reflected ray both make an angle of with the normal as per the first law of reflection and the ray, upon reflection, retraces its path.
Reflection is a phenomenon in which a ray of light falls on a surface and returns to the same medium in a different direction.
The laws of reflection are as follows:
The angle between the normal and the incident ray is called the angle of incidence.
The angle between the normal and the reflected ray is called the angle of reflection.
When a set of parallel rays undergoes reflection, but the reflected rays are not parallel to each other, the resulting reflection is known as diffuse reflection.
An object that is not self-illuminating reflects light that is incident on it. We are able to see these objects since our eyes receive light reflected from the object.
Vehicles drivers on a road normally view the ambulance in their rear-view mirrors, so whatever they see will be a mirror image. Thus, if the text on the front of an emergency vehicle is written in reversed lettering, the image seen by the driver in the rear-view mirror will appear in proper orientation.
The five characteristics of an image formed by a plane mirror are as follows:
The three uses of a plane mirror are as follows:
No, images formed by a plane mirror can never be projected onto a screen, as light rays do not actually reach the image. The image is a virtual image positioned behind the mirror.
A plane mirror forms a virtual image behind the mirror. The image distance between the mirror and the image distance will always be equal to the distance between the mirror and the object. Priya can see the objects placed at points A and B but not the object placed at point C as per the image below. Object C is out of range of Priya’s visibility.
The image of an object will be the same size as the object, irrespective of the size of the plane mirror.
When an image is formed by a plane mirror, the left-to-right orientation of the object is reversed in the image. This is known as lateral inversion.
We should take the following measures to look after our eyes:
i. Wash our eyes two or three times a day
ii. Never touch our eyes with dirty hands
iii. Never rub our eyes
iv. Read books and watch television from an appropriate distance
v. Consult an ENT specialist in case of redness or irritation
A Kaleidoscope is made by joining three plane mirror strips to form a triangle. A piece of hollow cardboard tube is wrapped around the mirrors. On one side of the cardboard tube we place small pieces of plastic or glasses of different colours, wrapped between two transparent sheets. The other side is closed with a transparent plastic sheet. When we look through the plastic sheet, we see beautiful coloured patterns formed as a result of multiple reflections of the pieces on the mirrors.
Blinking allows the eyelid to help keep the eye clean and protects our eyes from becoming dry. Another benefit of blinking is that it can stop foreign bodies from falling into our eyes.
As we enter a dark room from sunlight, we are unable to see things for a little while. This is because the pupils will have closed in the sunlight. As the pupils open in the dark room, more light enters the eye and we can see things again.
Once light enters the eye, the lens focuses the light on the retina.
In nature, raindrops break sunlight into the combination of colours seen by the human eye. This is because every raindrop acts like a prism and breaks the light into rainbow colours. A prism does the same thing, breaking white light into its different constituent colours.
At the point in the eye where the optic nerve connects to the retina, we don't have rods or cones. This place is called the blind spot. Thus, images falling on this portion of the retina or the blind spot are not visible to us.