Science questions in short. [2 marks ]

A ray of light that strikes a surface or falls on a surface before being reflected, transmitted or absorbed is known as incident ray.

Regular reflection, wherein the reflected rays are parallel to each other, lead to the formation of images because all the rays get reflected in a particular direction. Regular reflection always occurs from a smooth surface. Diffused reflection does not lead to the formation of images because the rays do not reflect in one particular direction.

The information that we get about sunlight from the formation is about dispersion of light. The separation of white light into seven different colors is known as dispersion.

We are able to see the moon because the light of sun falls on moon and is reflected onto the earth. Hence, we are able to see the moon.

The angle which incident ray makes with the perpendicular to the surface at the point of incidence.

A small opening in the iris of an eye is known as pupil. Pupil controls the amount of light that enters the eye.

The angle of reflection when a ray of light is incident normally on a plane mirror will be zero degree because the angle of incidence will be zero degree as the ray is incident normally. By law of reflection, angle of incidence = angle of reflection.

The phenomenon that applies here is multiple reflection that provides the image of back of the head to be viewed. A person is made to stand in front of a mirror and another mirror is held at the back of the head. The reflection from the mirror at the back is visible in the mirror in front of the person and hence the hair at the back of the head is visible to the person in the front mirror.

The point of incidence is the point where the incident ray strikes the mirror.

The angle between the reflected ray and the line perpendicular to the reflecting surface at the point of incidence is known as the angle of reflection.

The angle of incidence when a ray of light is incident normally on a plane mirror is zero degree because the ray is incident normally.

Iris, the part of our eye, contains pigment and gives the eye its distinctive color. Iris also helps in controlling the size of the pupil by constricting and dilating it, thus reducing and increasing the amount of light entering the eye.

Cataract is the clouding of the lens of human eye, that lies behind the iris and pupil. It leaves to a blurred vision or decrease in vision. The lens that has becomes cloudy is replaced by an artificial lens to restore the normal and clear vision.

The human eye has convex type of lens. Light that hits the lens of the eye is focused by the lens so that it hits the retina. Retina has photoreceptor cells (rods and cones) which get stimulated and sends signals to the brain for viewing.

In the presence of little light the iris has to dilate pupil to facilitate entry of more and more light to view things, which leads to strain on the eyes and causes headaches. In case of too much light, the retina may get injured and damaged thus impairing vision.

The objects in a dark room cannot be seen because there is no light. We can only see something when a certain amount of light falls on it. The objects outside the room can only be seen if there is light outside the room.

A Kaleidoscope is a toy mostly used by children for enjoyment. It is made of a tube with plain mirrors and colored glass pieces inside it at one of the ends. Kaleidoscope having object chambers are used for hiding valuables.

The iris adjusts the size of pupil according to the light of varying intensity. When the amount of light is very high, the iris contracts the pupil and reduces the amount of light entering the eye. Whereas, when the amount of light is less, the iris expands the pupil so that more light can enter the eye and things can be viewed clearly.

The phenomenon is known as Lateral inversion. The effect produced by a plane mirror in reversing the images from left to right and right to left while forming images is lateral inversion.

The eye lens is made up of living cells and the focal length of eye lens is adjustable. Whereas, an ordinary convex lens is made of glass and its focal length cannot be changed as it is fixed.

In dim light the size of the pupil of our eye becomes larger or dilates to increase the amount of light going inside the eye. This dilation in size is facilitated by the muscles of iris.

A book lying on a table in a room can be seen from all the parts of the room because of reflection by the light falling on the book. The light is reflected by the book and it reaches our eye at any part of the room.

The image of an object in a plane mirror is virtual. Virtual image cannot be projected onto the screen because it is not real. A virtual image is a copy of the object, formed on the plane mirror. The light rays never come from the image. They appear to come from the object.

In bright light the size of the pupil of our eye constricts and becomes small to reduce the amount of light going inside the eye. This reduction in size is facilitated by the muscles of iris.

If something like a dust particle or an insect gets into our eye, we should never rub the eye, instead wash the eye with cold water. If washing with cold water does not help, we should consult a doctor immediately.

The light ray reflected by a surface, when an incident ray strikes the same surface is the reflected ray. The reflected ray corresponds to the incident ray always.

Diffused reflection takes place from a rough surface. The reflected rays are not parallel in diffused reflection. Regular reflection takes place from a smooth surface. The reflected rays are parallel in regular reflection.

When a ray of light is incident normally (perpendicularly) on a plane mirror, the ray reflects and follows the same path.

The apparatus used to obtain a thin beam of light is known as Ray box. The rays are bright enough to be viewed easily. A ray box is a standard source of light used in optics experiments.

In bright sunshine the size of the pupil of the eye is very small so when we enter a darkened cinema hall from bright sunshine very little amount of light enters the eye. The vision improves at some time later because the pupil dilates and more amount of light enters the eye easily.

Blind spot is the point in human eye where the image is not visible. This is because there are no photoreceptors, i.e., rods and cones present in the optical disk.

Cornea is the transparent front part of an eye. It covers the front portion of the eye.

For a single incident ray falling on a plane mirror, there is always a single reflected ray. The angle of incidence is always equal to the angle of reflection, this is by the law of reflection.

Blind spot is the point in human eye where the image is not visible. This is because there are no photoreceptors, i.e., rods and cones present in the optical disk.

Normal is an imaginary line perpendicular to the surface, in the reflection of light from a plane mirror.

Rods are rod shaped cells present in the retina are sensitive to dim light. They are most important for vision in dim light. Cones are cone shaped cells present in the retina are sensitive to bright light. These photoreceptor cells are responsible for color vision.

Infinite number of images of the candle will be formed because the mirrors are placed parallel to each other.