CBSE Class 5 EVS Lenses Microscopes Worksheet

Chapter - 14 (Lenses & Microscopes)

Q.1: Define the following:
i) Concave lens:
Answer: A concave lens is thinner in the middle and thicker at the edges. It causes light rays passing through it to diverge (spread out).
In simple words: A concave lens is curved inward and makes light rays spread apart.

Exam Tip: Remember that a concave lens diverges light, whereas a convex lens converges light.

ii) Convex lens:
Answer: A convex lens is thicker in the middle and thinner at the edges. It causes light rays passing through it to converge (meet) at a single focal point.
In simple words: A convex lens is bulging outward in the center and brings light rays together.

Exam Tip: Convex lenses are used in magnifying glasses and microscopes to make objects look larger.

iii) Pathologist:
Answer: A pathologist is a medical doctor who studies body tissues, blood, and other samples under a microscope to diagnose diseases in patients.
In simple words: A pathologist is a specialist doctor who studies diseases using laboratory tests and microscopes.

Exam Tip: Connect the term pathologist with the study of diseases and laboratory testing.

iv) Cells:
Answer: Cells are the basic structural, functional, and biological units of all living organisms. They are often called the building blocks of life.
In simple words: Cells are tiny compartments that make up the bodies of all living things.

Exam Tip: Always describe cells as the basic building blocks of living organisms.

Q.2: Fill in the blanks:
i) All convex lenses can focus light rays up to a point.
Answer: light rays
In simple words: Convex lenses bend light so that the rays meet at one clear point.

Exam Tip: Focus on the converging property of convex lenses.

ii) Convex lenses are used to project pictures on a screen.
Answer: Convex lenses
In simple words: Projectors use convex lenses to form enlarged images on screens.

iii) Lenses are generally curved pieces of glasses.
Answer: curved
In simple words: Lenses are specially shaped pieces of transparent glass or plastic.

Exam Tip: The curved shape of a lens is what refracts (bends) light.

iv) Pathology is the study of disease.
Answer: Pathology
In simple words: Pathology is the scientific study of the causes and effects of diseases.

Exam Tip: Differentiate between a pathologist (the person) and pathology (the study).

Q.3: Mention the uses of:
i) Magnifying glass
Answer: A magnifying glass is used to make small objects, fine print, or details appear larger so they can be examined easily.
In simple words: It is used to zoom in on tiny things like small letters or insects.

Exam Tip: A magnifying glass is a simple convex lens held in a frame with a handle.

ii) Microscope
Answer: A microscope is used in laboratories and schools to view extremely small objects, microorganisms, and cells that cannot be seen with the naked eye.
In simple words: It is used to magnify microscopic things like bacteria and blood cells.

Exam Tip: Microscopes combine multiple lenses for very high magnification.

iii) Telescope
Answer: A telescope is used by astronomers to view distant objects in space, such as stars, planets, and galaxies.
In simple words: It is used to make far-away objects in the sky look closer and clearer.

Exam Tip: Remember: microscope for tiny near objects, telescope for huge distant objects.

Q.4: How do cells of blood and onion skin look under a microscope? Draw a diagram to show each.
Answer: 1. Blood cells: Under a microscope, red blood cells appear as tiny, disc-like circular shapes without nuclei, while white blood cells appear larger with distinct nuclei.
2. Onion skin cells: Under a microscope, onion skin cells look like brick-like rectangular compartments arranged neatly with clear cell walls and nuclei.
In simple words: Blood cells look like tiny round discs, and onion cells look like rectangular bricks.

Exam Tip: Mention both shape and structure when describing biological cells.

Q.5: Identify the following lenses:
Answer: 1. First lens (Left): Convex lens (thicker in the middle, thinner at the edges).
2. Second lens (Right): Concave lens (thinner in the middle, thicker at the edges).
In simple words: The left one is a convex lens and the right one is a concave lens.

Exam Tip: Visually check the middle thickness: bulging center means convex, pinched center means concave.

Q.6: Draw and name the two instruments that have lenses.
Answer: Two common instruments that use lenses are the Microscope and the Telescope.
In simple words: Microscope and telescope are optical instruments fitted with lenses.

Exam Tip: Be ready to sketch a simple compound microscope or telescope when asked.