Science questions in short. [2 marks ]

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.

Laser light is harmful for the human eyes, because its intensity is very high. It can cause damage to the retina and lead to blindness. Hence, it is advisable not to look at a laser beam directly.

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

Virtual image is formed by an extension of reflected ray where the ray never meets in real. That is a reason virtual image cannot be taken on screen.

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.

Law of the reflection means the angle of incidence is equal to the angle of reflection. For irregular reflection law of reflection does not hold true.

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. Example- The images are reversed by the plane mirror.

Kaleidoscope is based on the phenomenon of multiple reflections when plane mirror is place together making some angle.

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 image of the child cannot be obtained on the screen because the image is not real. The images formed by plane mirror are virtual, so these virtual images cannot be seen (or obtain) on the screen.

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

Diffuse reflection of light takes place. When a ray of light fall (strike) on the surface of Chalk powder, reflected ray get scatted in a different direction with a different angle. So, the law of reflection doesn't hold true. Thus, diffuse reflection.

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.

Cone cell Our eye contains two types of cells – cone cell and rod cell. Cone cell is responsible for the colour and it is sensitive to bright light. Rod cell is sensitive to dim light.

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.

We are having only one plane mirror as per given in the question. For every incident ray, there is only one reflected ray. There will be only one reflected ray for a single ray falling on a plane 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.

Infinite number of the image is formed when an object is placed between two parallel plane mirrors facing each other.

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 pupil is the part of your eye that controls how much light gets in. When we enter in an area of bright light, size of pupil gets smaller (contract) because to control the amount of light.Additional information:
While entering the dark room pupil becomes large (expands) so that more and more light can enter the eye. Size of the pupil is controlled by iris. Thus we can say that iris controls the amount of light entering into the eye.

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 size of the eyes of nocturnal bird is large. Eyes of the nocturnal birds having large cornea with a wider pupil, can collect more ambient light which help them to see the objects even at night.