# focal length of combination of lenses experiment

Fizeau interferometry The length focal length is calculated using the following formula: 1 6 + 1 7 = 1 U and V are measured from the principal planes. The combined focal length for two thin lenses separated by a distance a (Figure 2) is given by the equation: So, focal length of a lens increases when it is immersed in water. 1/F = 1/f 1 + 1/f 2. 2. Concave(Lensesand(LensCombinations(! The lenses are touching. Conclusion The objective of this experiment is to determine the focal length of a convex lens using different locations of the object and graphical method. 7. Goal:!!To!determine!the!focal!length!of!a!concave!lens!and!to!better!understand!how! Determine the effective focal length of a combination of two converging lenses arranged as shown below: 1. Experiment: Determine the focal length of a concave lens by combining it with a suitable convex lens. Here µ is refractive index of lens material to the medium outside. Last problem on study guide help! Combined focal length (F): =f 1 f 2 /[f 1 + f 2] F = 10x(-20)/[10-20] = +20 cm The focal length of the combination is positive and so it acts as a convex lens. Before getting started with the experiment, it is important to understand a few terms that are used in a concave mirror and convex lens: Centre of curvature: For a curved mirror, the centre of curvature, C can be defined as the centre of a hollow glass sphere of which a curved mirror is a part. 3. According to the author, this method gives the focal length value with less than 1% accuracy. The lens equation has been proved and it can be concluded that there is a specific property of lenses that is applicable in getting the focal length. Find the theoretical value of the focal length for this combination of lenses. Measure the focal length and compare it to the theoretical value. This property is the reversibility property of thin lenses. Part C: Combinations of lenses. The focal lengths of each lens is significantly larger than the distance between the lenses. Each lens is a converging lens & the focal length of each lens is known, f 1 and f2. This is lens maker’s formula. Use a combination of lenses (for example, a 100 mm lens and a 200 mm lens). If two lenses of fecal lengths f 1 and f 2 are kept in contact, the focal length F of the combination is given by. Combination of Thin Lenses. Shaikh Ilyas; AIM: To determine the focal length of converging lens and it’s radius of curvature. It can be shown that the lens focal length is related to the distance between different Moiré images. A combination of convex and concave lenses has power 4 D.If the convex lens has power 5 D focal length of the concave lense will be View Answer A bi-convex lens is formed with two thin plano-convex lenses as shown in the figure. Mount the 2 lenses next to one another. HYPOTHESIS: The relationship between u and v and the focal length f for a convex lens is given by .Where f is the focal length, u is the distance between the object and the lens v is the distance between the image and the lens. Focal Length of Concave Lens Experiment. Consider two thin convex lenses L 1 and L 2 of focal length f 1 and F 2 placed coaxially in contact with each other.