Class 8 Science Chapter 13 MCQ

The point at which the incident ray strikes the mirror is called the point of incidence. The angle of reflection is always equal to the angle of incidence.

Iris is a dark muscular structure behind the cornea, which controls the amount of light entering into the eye.

Here, all the statements are correct. Hence, your answer will be option [D].

We can see a non-luminous object (object that does not produce its own light), when the light reflected by the object enters our eyes.

Here, all the statements are correct. Hence, your answer will be option [D].

The farthest point on the eye at which an object can be seen clearly is known as the “far point” of the eye. The nearest point up to which the eye can see an object clearly without any strain, is called the near point of the eye. The near point of a normal human eye is at a distance of 25 cm from the eye. This means, the most comfortable distance at which one can read a book with normal eyes is about 25 cm from the eyes.

Cones are sensitive to bright light and they sense color. However, rods are sensitive dim light.

Here, all the statements are correct. Hence, your answer will be option [D].

We know that a plane mirror forms only a single image of an object placed in front of it. When two plane mirrors are kept inclined at an angle, they can form multiple images of an object. This is because the image of an object formed in one plane mirror acts as a object for the other plane mirror. Number of images formed = 360 degree / x – 1

Here, all the statements are correct. Hence, your answer will be option [D].

The objects which do not emit their own light are called “non luminous” objects. Actually, the moon the non-luminous objects cannot make their own light. The moon, earth, table, chair, book, trees, plants, flowers, human beings, mirror, diamond are some of the examples of non-luminous objects.

Here, all the statements are correct. Hence, your answer will be option [D].

When the angle between mirrors is 180° then only single image is obtained. If the angle decreases, then the number of images increases. If the angle increases, then the number of images decreases. And when the angle between two plane mirrors become 0 degree, that is, when the two plane mirrors become parallel to each other then, an infinite number of images are formed.

Auditory nerve is not a part of the human eye. Explanation: Auditory nerve is a nerve bundle that transmits sound from cochlea to the brain. Cochlea is a auditory sense organ found at the back of each ears.

The shape of the lens is changed by ciliary muscles so that the image forms at a sharp focus at the retina. The lens becomes thicker to focus at near objects and becomes thinner to focus at distant objects.

The colored part of our eyes is called pupil. Iris control the size of pupil. The pupils expand and contract according to the light entering the eyes. When light is less/low, then the muscles of the pupil relaxes and it becomes larger. When light is bright/more, then the muscles of the pupil contract and it becomes smaller. The shape of the pupil varies for different animals

Here, all the statements are correct. Hence, your answer will be option [D].

Screen in a cinema hall produces diffuse reflection of light. When light incidence on smooth surface, the light is reflected in one direction as parallel beam. This is why our eyes cannot view the reflection from mirror, water and polished wood directly. When the light incidence on rough surface, the light is reflected in many directions. So, in cinema hall, the screen is designed as rough and irregular surface. In theatre, the projector projects parallel light rays which falls on screen. Due to irregularity of screen, the light is reflected in different direction. This type of reflection helps people from anywhere in the theatre to see the picture projected by the projector

In the human eye, when the light rays enter to a sharp focusing point on the retina. It acts as the film on camera. It receives the image and passes to cornea. Here, the internal lens of the eyes is focused by cornea. It transforms this image falling on the lens into electrical impulses. The electrical impulses are transferred to optic nerves which carry information to brain and we can see the object.

Here, all the statements are correct. Hence, your answer will be option [D].

The size of the pupil of the eye is adjusted by “Iris”. The pupil of our eye is an entrance for the light rays to enter our eyes and give us the sensation of sight. If too much light enters our eyes, it can be dangerous for eyes. Whenever the light is strong, the pupil shrinks in order to reduce the entrance of light and protect our eyes. If too less light enters our eyes, we don’t get a clear vision. Whenever the light is weak, the pupil expands in order to increase the entrance of light and improve the vision. This is how pupil of the eye changes its size to adjust for different amount of light.

Here, all the statements are correct. Hence, your answer will be option [D].

The medical condition in which the lens of eye of a person becomes progressively cloudy resulting in blurred vision is called cataract. Cataract develops when the eye-lens of a person becomes cloudy or even opaque due to the formation of a membrane over it. Cataract decreases the vision of eye gradually. The vision of the person can be restored after getting surgery done on the having cataract. The eye defect called cataract cannot be corrected by any type of spectacle lenses.

The defect of an eye in which it cannot see the distant objects clearly is called myopia. A person with myopia can see nearby objects clearly.

Reflection is bouncing back of light rays from the surface of an object.