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.

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

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.

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

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].

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

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 object for the other plane mirror. Number of images formed = 360 degree / x – 1 = 360 / 90 – 1 = 4 – 1 = 3

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.

The deficiency of one of the following in the diet of a person for a considerable time can lead to a disease called night blindness. This one is “Vitamin A”. The impaired dark adaptation of eyes is called as night blindness. People with this impairment can hardly see in dim environment or during night time. This due to vitamin deficiency is mostly treatable with vitamin supplement. Vitamin A helps in transfer of nerve impulses into image to retina. Some of the food with Vitamin A are eggs, cod liver oil, yellow and orange fruits and vegetables and so on.

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].

According to the law of reflection, the angle of incidence is equal to the angle of reflection. If the incident ray makes an angle of 65 degree with the surface of plane mirror, than the angle of incidence can be calculated as: Angle of incidence = 90 – angle made with the plane mirror = 90 – 65 = 25 degree. Since, the angle of incidence is equal to the angle of reflection, therefore the required angle of reflection = 25 degree

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

We can clearly view an object only when image is clearly reflected on retina. Our eyes focus distinct and near objects and reflects the image on retina. When eyes need to focus distinct object, then ciliary muscles reflex which increases the focal length. The eye lens converges the light and the objects are said to be unaccommodated. When eyes need to focus nearby object, then ciliary muscles relax which decreases the focal length. The eye lens diverges the light and the objects are said to be accommodated. The accommodation power of eyes is as close as 25 cm and as far as infinity.

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

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

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

The impression or sensation remains on the retina for about 1/16th of a second even after removal of the object.

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