What will be the power of a convex lens of 25 cm focal length?

In this question it is given that the lens is convex, and its focal length is $25$ cm. First we will convert the focal length in meters. As it is a convex lens so its power is positive. Thus, the power of the lens is $+ 4D$.

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

Now since the focal length is inversely proportional to the (μ−1), therefore the focal length will increase. Hence the focal length of the lens increases when it is immersed in the water.

What is the image formed by a convex lens if an object is placed at the focus?

When the object is located at the focal point, no image is formed. As discussed earlier in Lesson 5, the refracted rays neither converge nor diverge. After refracting, the light rays are traveling parallel to each other and cannot produce an image.

Where should be the object placed on the principle axis of a convex lens in order to get virtual image?

A virtual image is formed if the object is located less than one focal length from the converging lens. To see why this is so, a ray diagram can be used. A ray diagram for the case in which the object is located in front of the focal point is shown in the diagram at the right.

What is the power of a convex lens of focal length 20cm?

The power of a lens of focal length 20cm is 5D.

What is the power of a convex lens of focal length?

Answer: Convex lens have the ability to converge a parallel beam of light into a point. This point is called the focal point of the convex lens and the distance from the optical centre to the focal point is called the focal length. p = 10 D.

What effect do we find on the focal length of a lens when the lens is placed in water instead of air and explain with reason?

Since the relative refractive index of glass with respect to water is less than that of glass with respect to air, the bending of light at the interface of glass water is lesser and hence a parallel beam of light falling on the lens is bent less, to meet at point on the principal axis and hence the lens has more focal …

What happens to the focal length of the convex lens when it is cut horizontally?

Answer: If a convex lens is cut horizontally then radii of curvature on both sides of the lens i.e., R1 and R2 will remain same as before. As R1 and R2 do not change, so there will be no change in focal length of the lens.

When an object is placed on the principal focus of a convex converging lens?

When the object is placed at the focus the image is formed at infinity &highly enlarged.

How an image is formed by a convex lens?

In case of a convex lens, if we bring the object close to the lens, the size of the image keeps on increasing. As you bring the object more close to the lens, we get the image all the more enlarged. We can have diminished inverted image, small sizes inverted image, enlarged inverted image, enlarged erect image.

Where should object be placed on principal axis?

Let a point object O be placed on principal axis at a distance is u from P1. A ray OA travelling in rarer medium is incident on first surface of lens. It is refracted towards normal at A. If the second surface of lens were absent, the ray AB would have met the principle axis at I’ which is image of V.

Why object is placed on the principal axis?

When an object is placed on the principal axis of a convex lens at two different positions, it produces the image with magnification +2 and -4 respectively. Hint: We have given the magnification of an image from which we can find the relation between the image distance and the distance of the object.

How do you use a convex lens to observe objects?

Place the object between O and F of the lens and record your observations. Draw ray diagrams for all the positions of the object. The focal length of the convex lens must be between 15 to 20 cm. Use thin convex lens of small aperture. Perform this experiment in calm air to avoid the flickering of the candle flame.

What is the focal length of the convex lens?

The focal length of the convex lens must be between 15 to 20 cm. Use thin convex lens of small aperture. Perform this experiment in calm air to avoid the flickering of the candle flame. To obtain distinct and sharp image of the candle flame, perform this experiment in a dark room.

How do you find the focal length of an object?

Measure u and v . Repeat above step at few more object distances. Get the focal length from all measurements by (a) taking average of calculated f or (b) from u versus v graph or (c) from versus graph. Look at the ray diagram shown in the figure. The distances are measured from the pole P.

What is convex lens Experiment Class 10 science?

CBSE Class 10 Science Lab Manual – Image Formation By Convex Lens Experiment Lens: A transparent material bound by two surfaces, of which one or both surfaces are spherical, forms a lens. Convex lens: Convex lens is a transparent curved device that is used to refract light.