The power of convex lens of focal length 20 cm is

Download free printable assignments and worksheets of class 10 Science. Free PDF Download- Best collection of notes, important questions , sample papers and NCERT Solution for CBSE Class 10 Science. Below you will find the home work assignment for CBSE Class 10 Light- Reflection and Refraction. Problems on convex lens: Q.1. A convex lens of focal length 10 cm is placed at a distance of 12 cm from a wall. How far from the lens should an object be placed so as to form its real image on the wall? Answer 60 cm Q.16. An object 2 cm tall is placed on the axis of a convex lens of focal length 5 cm at a distance of 10 cm from the optical centre of the lens. Find the nature, position and size of the image formed. Which case of image formation by convex lenses is illustrated by this example? Answer v=5.02 cm, h=-0.01 cm, real, inverted & diminished (b/w f and 2f)

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The correct option is B. 15. In the absence of a concave lens, the parallel beam will be focussed at the focus F2 of the convex lens i.e. at a distance of 20 cm. from lens A. The focal length of the concave lens is 5 cm. i.e. if this lens is placed at 5 cm from F2 towards the left, then the beam will become parallel. From the figure, it is clear that the separation between lenses d = 20-5 = 15 cm.

The lens power equation If a lens has a shorter focal length it is said to be more powerful. The power of a lens is defined as the reciprocal of the focal length. Lens power is measured in dioptres ( D ). \[power \\ of \\ a \\ lens \\ (D) = \frac = -0.30 \\ m\] \[focal \\ length = -30 \\ cm \\ (concave \\ lens)\] Question A convex lens has a focal length of 5.0 cm. Calculate the power of the lens. Reveal answer

Lenses, both converging and diverging, are the marvels of optical physics that use the ability of these media to refract, reflect, or bend light rays. In general, the lenses come in two shapes: convex (curved outward) and concave (curved inward). One of their principal purposes is to magnify images, i.e., make images appear larger than their actual size. Nowadays, these lenses can be seen in microscopes, telescopes, binoculars, other optical instruments, and of course, in our own eyes. Scientists and students have many simple to complex algebraic equations to associate the shape and physical dimensions of a lens to the effects it puts on the light rays that pass through it. Here, we will learn and understand some of the most vital equations and formulae related to the lens, along with the lens power. We will also learn how to calculate magnification with the help of lens formula. What is the Lens Formula? Spherical lenses in optical physics are the lenses formed by coupling two spherical surfaces together. Based on this concept of formation by binding two surfaces, these lenses are of two types: convex lenses - the lenses formed by binding the two spherical surfaces curved outward and concave lenses - the lenses formed by binding the two spherical surfaces curved inward. (The Image Will be Uploaded Soon) (The Image Will be Uploaded Soon) Images formed by these lenses can be real, virtual, or of different sizes depending on the objects’ distance from the lens. Now, the Lens...

We have focal length of convex lens, `f_1 = +25 cm = +0.25 m`and focal lenghth of conceave lens, f 2 =-20 cm =-0.20 m Equivalent focal length, `f= 1/f_1 +1/f_2 =1/25 +1/-20=-1/100` ∴ F =- 100 cm Power of convex lens, `P_1 = 1/f_1 = 1/0.25` Power of convex lens,`P_2 = 1/f_2 = 1/- 0.20` Power of the combination, `P = P_1+P_2 = 1/0.25 + 1/-0.20 = 100/25 +100/-20 = (400 - 500)/100 = (-100)/100 = -1D` The focal length of the combination =–1 m = –100 cm. As the focal length is in negative, the system will be diverging in nature.