class 10 -Spherical lens

When an object is placed at infinity in front of a convex lens, the image formed is:

• A) At infinity, real and erect

• B) At the focus, real and inverted

• C) At the center of curvature, real and inverted

• D) At the focus, virtual and erect

A concave lens always forms an image that is:

• A) Virtual and erect

• B) Real and inverted

• C) Real and erect

• D) Sometimes real, sometimes virtual

A convex lens forms a real and inverted image of an object. The object is placed:

• A) Between F and 2F

• B) At F

• C) Between O and F

• D) At infinity

The image formed by a convex lens is of the same size as the object when the object is placed at:

• A) Infinity

• B) Focus (F)

• C) Twice the focal length (2F)

• D) Between F and 2F

If the focal length of a convex lens is 20 cm, where should an object be placed to form an image at 40 cm on the other side?

• A) 20 cm

• B) 30 cm

• C) 40 cm

• D) 60 cm

A convex lens is also known as:

• A) Converging lens

• B) Diverging lens

• C) Bifocal lens

• D) Plano lens

What happens to the focal length of a convex lens when it is placed in water instead of air?

• A) Becomes zero

• B) Decreases

• C) Remains the same

• D) Increases

A convex lens is used to correct which type of vision defect?

• A) Myopia (nearsightedness)

• B) Hypermetropia (farsightedness)

• C) Astigmatism

• D) Presbyopia

A concave lens of focal length 15 cm is placed 10 cm away from an object. The image formed will be:

• A) Real, inverted, and diminished

• B) Virtual, erect, and diminished

• C) Virtual, inverted, and magnified
  

• D) Real, erect, and magnified