Class 7 Science Chapter 11 MCQ

Concave mirror and convex lens can only from enlarge image of an object. As convex mirror and concave lens always from a diminished image of an object.

We know that a convex lens gives a magnified image of a closed object. Used in this way, a convex lens is commonly known as a magnifying glass. A magnifying glass is a convex lens which is used to make small things look bigger by producing their magnified images. In other words, to use a convex lens as a magnifying glass, the object should be at a less distance than the focal length of convex lens. Convex lenses are used as magnifying glasses and convex lens also used in making spectacles, cameras, microscope, telescope and binoculars etc.

When an object is placed at a far-off distance from a concave mirror, the image formed by a concave mirror is real, inverted and much smaller than the object. When an object is placed at a distance greater than twice the focal length of a concave mirror, the image formed by concave mirror is real, inverted and smaller than the object. When an object is placed at a distance between focal length and twice the focal length of a concave mirror, then the image formed by concave mirror is real, inverted and larger than object. When an object is placed close to concave mirror (at less than focal length), the image formed by a concave mirror is virtual, erect and larger than the object.

Remember, that whether an object is placed at a large distance or it is close to convex mirror, a convex mirror always forms an image which is virtual, erect and smaller than the object. Changing the position of object in front of a convex mirror only changes the size of image. But in every case, the image remains smaller than the object. (Note: A plane mirror and a convex mirror always forms a virtual and erect image of an object.)

We know that concave mirrors are used as shaving mirrors to see a large image of the face. Concave mirrors are used by dentist to see the large images of teeth patients. Concave mirrors are used as reflectors in torches, headlights of vehicles. Doctors use concave mirror as reflector to produce a parallel beam of light for examining the body parts such as eyes, ears, nose etc. Concave mirrors are also used in dish antenna to receive TV signals from satellites. Convex mirrors are used as rear-view mirrors or side view mirrors in vehicles (such as cars, scooters, buses etc.) to see the traffic at the rear side or back side on the road.

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

The objects having polished, shining surfaces reflect more light than objects having unpolished dull surfaces.

The image which can be obtained on a screen is called real image which we can see in cinema screen, not virtual screen. The image formed on cinema screen is an example of real image. A real image is formed when light rays coming from an object actually meet at a point after reflection from the mirror. A real image can be formed on a screen because light is actually passed through it.

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 incorrect. Hence your answer will be option [D].

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

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

True, the image formed by a concave mirror shows lateral inversion, i.e., left seems to be right and right seems to be left.

As only a concave mirror can form a real image. Plane mirror and convex mirror always form a virtual image of an object.

As in case of plane mirror, image formed is virtual, erect and of same size and in case of convex mirror, image is virtual, erect and smaller in size.

A rainbow can only be seen in the sky when the sun is behind you in rainy season.

An erect and enlarged image can only be formed by a concave mirror and it is virtual in nature.

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].

An object is placed at a large distance or it is close to the concave lens, a concave lens always forms an image which is virtual, erect and smaller than the object. Changing the position of object in front of a concave lens only changes the size of image. But in every case, the image formed by concave lens remains smaller than the object. Since, a concave lens always forms a smaller image than the object. Therefore, object always look smaller when seen through a concave lens.

Whether an object is placed at a large distance or it is close to convex mirror, a convex mirror always forms an image which is virtual, erect and smaller than the object. The outer surface or back side of a shining steel spoons acts like a convex mirror. So, if you look into the outer side or back side of a shining steel spoon, we will see a virtual, erect in smaller image of our face. Only this happens due to bulging out structure of convex mirror.

A concave lens can only from virtual, erect and diminished image of an object. As virtual and erect image formed by a convex lens is always magnified.

Concave mirror and convex lens can only from real and inverted image of an object. As convex mirror and concave lens always from a virtual and erect image of an object.