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A lens is an optical device that transmits and refracts light. It converges or diverge the beam of light. A single lens consists of a single optical element whereas a compound lens is an array of simple lenses with a common axis. Compound lenses are useful because it allows more optical aberrations to be corrected than is possible with a single element.  Elements which refract electromagnetic radiation outside the visual spectrum are called lenses as well.

Lenses are classified by the curvature of the two optical surfaces. The different types of lenses are listed below in the table:

Biconvex Both surfaces are convex
Plano-convex One surface is concave and the other is convex
Positive meniscus One surface is concave and the other is convex
Negative meniscus One surface is concave and the other is convex
Plano-concave One surface is flat and the other is concave
Biconcave Both surfaces are concave


The focal length of a lens in air is calculated from the lensmaker’s equation below

P = 1/f


P is the power of the lens

f is the focal length of the lens

A Two Lens System

A cell phone of length 10.0cm sits 50.0cm in front of a lens of focal length 30.0cm. a. Without equations, use a diagram to determine whether the image of the cell phone is real or virtual, upright or inverted, and magnified or reduced. Estimate the magnification from your diagram. b. Now calculate the magnification and check

Determining Objective Lens Length and Focal Length

Hi, I need some assistance answering the following questions. I am having some difficulty understanding the concepts. Question: (a) How large is the exit pupil of a 7-power telescope having an objective lens 50 mm in diameter? (b) If the objective lens is 6 inches in focal length, what must be the focal length of the ocul

Calculating Microscope Lens Magnification

Question: The image formed by a certain microscope objective lens is 180 mm from its second focal point. The focal length of the objective lens is 9 mm. An ocular lens of focal length 50 mm, is used to project a real image on a screen 1 m from the second focal point of the ocular lens. What is the lateral magnification between t

What is the focal length?

A telephoto camera objective consists of a thin positive lens of 10 inches focal length followed at a distance of 5 inches by a thin negative lens of focal length 20 inches. Locate the focal points and principal points of the objective. What is its focal length?

Curvature of the Surface of a Lens

The radii of curvature of the surfaces of a thin lens are +10cm and +30 cm. The index is 1.50. (a) Compute the position and size of the image of an object in the form of an arrow 1 cm high, perpendicular to the lens axis, 40 cm to the left of the lens. (b) A second similar lens is placed 160 cm to the right of the first. Fin

Conflict and Lens Model of Conflict

What contemporary conflict is in the news and what are the mutual interests of both parties in this conflict? What do you see as the incompatible goals in this situation? What are the perceived scarce resources that influence this conflict? What two main destructive patterns, escalatory spirals and avoidance spirals,

Object Viewing Through Lens with Focal Length of 30cm

1) An object is located 15cm from the center of a lens, as shown in the diagram (please refer to the attachment) below. The focal length of the lens is 30cm. a) Calculate the location of the image. Show your work and explain your reasoning. b) Calculate the magnification and determine if the image is inverted or upright.

Magnification of the Image Formed by a Lens

An object is placed to the left of a convex lens and on the optical axis. The object is 36 cm from the lens and the focal length of the lens is 66 cm. What is the magnification of the image formed by the lens? You do not have to enter units for this problem.

Optics - position of the image

An object is initially placed on the optical axis 26.5 cm to the left of a convex lens that has a focal length of 13.2 cm. The image is real and inverted. If the object is moved toward the lens to a point 7.1 cm away, what is the position of the image?

Distance Problems for Converging Lens

A person 1.28 meters high in front of a converging lens whose focal length is 1.92 meters. A real inverted image of forms 4 m on the other side of the lens. How far is the person from the lens? How large is the image? Sketch a diagram explaining how the image forms.

Lens and Charge Example Questions

1. Two lenses of focal lengths f1 = f2 = 10 cm are separated by 15 cm as shown in the attached figure. An object is placed 60 cm in front of the first lens. (a) Find the position of the image formed by the first lens. (b) Use the image produced by the first lens as an object for the second lens to find the position of the fi

Multicultural marketing - what is it and how does this firm use it

PINELLAS PARK, Fla., Sept. 2 /PRNewswire/ -- Recognizing the increased risks African Americans face for a number of eye health issues, Transitions Optical, Inc., the leading supplier of photochromic eyeglass lenses, is launching its "Healthy Sight for Life: Focus on African-American Eyes" campaign at the National Council of Negr

Net Focal Length

Show that if two thin lenses of focal lengths f1 and f2 are placed next to one another (in contact, as shown in the attached figure), the net focal length f is given by 1/f = 1/f1 + 1/f2. See the attached file.

Determining Focal Length and Image of Candle

A thin lens of flint glass with n=1.58 has one concave surface of radius of curvature 15 cm, and one flat surface. (a) What is the focal length of this lens? (b) If you place this lens at a distance of 40 cm from a candle where will you find the image of the candle?

Lens equation: Determine characteristics of the image

Two converging lenses, A with a focal length of +2.0 cm and B with a focal length of +5.0 cm, are placed 14c m apart. An object is placed 3.0 cm to the left of lens A. a) Use graphical methods, to scale, to construct the ray diagram with a measurement of the final image position and height; and b) Use the lens equation to de

Finding Image Location: Example Problem

Part 1: A converging lens of focal length 8.09 cm is 17.4 cm to the left of a diverging lens of focal length -5.99 cm. A coin is placed 12.8 cm to the left of the converging lens. Calculate the location of the coin's final image. Part 2: Calculate the magnification of the coin's final image. Please solve and explai

Lens equation for focal length

Lens equation. The focal length f for a camera lens is related to the object distance o and the image distance i by the formula 1/f=1/0+1/i Telephoto lens. Use this formula to find the image distance i for an object that is 2,000,000 mm from a 250-mm telephoto lens.

Converging Lenses: Magnification

Two 25.0 cm focal-length converging lenses are placed 16.5 cm apart. An object is placed 30.0 cm in front of one. Where will the final image formed by the second lens be located? What is the total magnification?

A solution is given to converging lens light.

Please solve and explain Converging lens placed near center of optical bench. Light source and object on left side of lens and screen on the other side. Light source placed as far away from lens as possible (about 39 cm). The screen is moved until image comes into focus on screen. Length of object is 6 cm, d

Converging lens

Please explain the answer to the following: You hold a converging lens in front of a sheet of paper so as to form a sharp image of a distant object or scene from a window. You can use a ruler to measure the focal length of the lens. What would be a likely focal length (estimate). With this focal length, what is the refracti

Physics: Optical Instruments

If you want a magnification of "time 3" in a telescope, and you have a lens of focal length 37 mm to use as an eyepiece, what focal length do you need for an objective lens? Draw a ray diagram of the telescope.

analyze current competitors

If Bausch and Lomb were to market a polarized contact lens; analyze current competitors and define the competitive landscape for the product. The top three competitors listed on are: Alcon Labs CIBA Vision Corporation Vistakon

Monopolistically Competitive Equilibrium

Soft Lens, Inc., has enjoyed rapid growth in sales and high operating profits on its innovative extended-wear soft contact lenses, However the company faces potentially fierce competition from a host of new competitors assume important basic patents expire during the coming year. Unless the company is able to thwart such comp

Astronomical telescope

An astronomical telescope is being used to examine a relatively close object that is only 107.00 m away from the objective of the telescope. The objective and eyepiece have focal lengths of 1.640 and 0.0840 m, respectively. Noting that the expression M = fo/fe is no longer applicable because the object is so close, use the thin-

Refraction, Lenses and Eysight

3. Your significant other (SO) meets you sporting a new set of glasses. YOu never realized that she/he needed glasses at all, but the person sought the advice of a physician because he/she had headaches at the end of the day. Referral to an optometrist resulted in glasses. You pick up the prescription from his/her desk and exami

What kind of lens must be used to produce this image?

In figure attached, a real inverted image I of an object O is formed by a certain lens (not shown); the object-image separation is d = 40.0 cm, measured along the central axis of the lens. The image is just half the size of the object. What kind of lens must be used to produce this image? How far from the object must the le

Galileo's Original Telescope

See attached for exact description and figure. The diagram above illustrates Galileo's original telescope. He used a convex objective lens with a focal length of 1.7m and a concave eyepiece as illustrated above. When this telescope is focused on an indefinitely distant object, its angular magnification is +3. a. What is th

Light 22.34

Work this problem using the thin-lens equation: A diverging lens with focal length of 25 cm is used to view a postage stamp 50 cm from the lens. (a) How far from the lens does the stamp appear? (b) What is the magnification of the image? Work this problem by ray tracing? I need to see each step and formula to solve this ques