subject

Lenses

Physics ⇒ Light and Optics

Lenses starts at 8 and continues till grade 12. QuestionsToday has an evolving set of questions to continuously challenge students so that their knowledge grows in Lenses. How you perform is determined by your score and the time you take. When you play a quiz, your answers are evaluated in concept instead of actual words and definitions used.
See sample questions for grade 12
A biconcave lens has a focal length of -15 cm. What is its power?
A convex lens has a focal length of 25 cm. What is its power in diopters?
A convex lens of focal length 10 cm is used to form an image of an object placed 15 cm from the lens. Calculate the image distance.
A lens forms an image 30 cm from the lens when the object is placed 10 cm from it. What is the focal length?
A lens forms an image that is diminished, virtual, and upright. What type of lens is it?
A lens forms an image that is real, inverted, and smaller than the object. Where is the object placed relative to a convex lens?
A lens has a power of +2.5 D. What is its focal length in meters?
A lens is used to correct hypermetropia (farsightedness). What type of lens is it?
A person uses a lens of power -3 D to correct their vision. What type of lens is this?
A thin lens produces an image twice the size of the object and on the same side as the object. What is the nature of the image?
Describe what is meant by the term 'optical center' of a lens.
Explain the difference between a real and a virtual image formed by a lens.
Explain why chromatic aberration occurs in lenses.
If a lens forms an image at infinity, where must the object be placed?
If an object is placed at 2f from a convex lens, where will the image be formed?
If the object distance is 10 cm and the image distance is 20 cm for a lens, what is the focal length?
State the lens formula relating object distance (u), image distance (v), and focal length (f).
The image formed by a convex lens is virtual and magnified. Where is the object placed?
The refractive index of the lens material is 1.5 and the radii of curvature of its two surfaces are +20 cm and -20 cm. Calculate the focal length of the lens.