English Medium कक्षा १० - CBSE Question Bank Solutions for Science

In human beings, the correct sequence of events during reproduction is

Explain how the uterus and placenta provide necessary conditions for proper growth and development of the embryo after implantation?

Give reason.

Placenta is extremely essential for foetal development.

Give reason:

Uterine lining becomes thick and spongy after fertilisation.

Given below is a certain situation. Analyze and describe its possible impact on a person:

Egg is not fertilised in a human female.

Given below is a certain situation. Analyze and describe its possible impact on a person:

Placenta does not attach to the uterus optimally.

List two roles of the Oviduct in the human reproductive system.

What is meant by a power of a lens? Define its SI unit. 

Define the power of a lens.

What does sign of power (+ve or –ve) indicate?

State the power of a lens S.I. unit.

How unit of power related to focal length of a lens?

Define 1 dioptre of power of a lens.

 A convex lens forms a real and inverted image of a needle at a distance of 50 cm from it. Where is the needle placed in front of the convex lens if the image is equal to the size of the object? Also, find the power of the lens.

Find the power of a concave lens of focal length 2m.

Find the focal length of a lens of power −2.0 D. What type of lens is this?

A doctor has prescribed a corrective lens of power +1.5 D. Find the focal length of the lens. Is the prescribed lens diverging or converging?

You have two lenses A and B of focal lengths +10 cm and –10 cm, respectively. State the nature and power of each lens. Which of the two lenses will form a virtual and magnified image of an object placed 8 cm from the lens? Draw a ray diagram to justify your answer

A student uses a lens of focal length 40 cm and another of –20 cm. Write the nature and power of each lens

What can you see in a completely dark room? If you switch on an electric bulb in this dark room as a light source, explain how you could now see:
(a) the electric bulb
(b) a piece of white paper