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If a telescope has an objective lens of 3 inches what is the focal length?
Wiki User
∙ 15y ago
The size (diameter) of a lens does not determine its focal length. The amount of curvature of the lens does. Citing a diameter for a lens doesn't help us find the focal length. Lenses are ground to specifications that allow short or long focal length. The more curved the lens, the shorter the focal length. You can see this if we specify a given curvature and then start to "flatten" the lens. The focal length will get longer and longer as the lens is flattened. When the lens is flat (has to curvature) the lense has an infinite focal length, just like a piece of flat glass.
Wiki User
∙ 15y ago
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Would the ocular unit increase or decrease as magnification increases?
Field of view will decrease as the aperture remain same but things become larger and so we can see smaller area after magnification
A converging lens of focal length f produces a real image of a real object when the object is what?
farther then f from the lens
Which part of an optical microscope contains the magnifying lens?
The body tube of a compound optical microscope contains two lens systems, the objective lens composed of one or several lenses that magnify the image of the object being examined, and the ocular lens at the eyepiece end. The magnification of the microscope depends on the focal lengths of the two lens systems.
What is Charcot-Wilbrand syndrome?
Charcot-Wilbrand is a type of syndrome that involves dream loss. This syndrome often occurs after a person suffers from focal brain damage. It is sometimes known as mind blindness.
How do you make a pewter keyring?
◦ ring 

SIMPLE FOCAL BEAD KEY RING
The lead picture for this article shows a completed key chain made with a focal bead. To make this, use:
a. A thick gauge head pin (the lower the number, the thicker the pin). A thick gauge pin is recommended so that it won't bend easily in your hand and won't come apart easily where it is attached to the key ring. However, be sure that your focal stone is drilled with a big enough hole that it can slip over the head pin.
b. A small gold bead that won't slip off the end of the head pin. This is the first bead you put on the pin.
c. A larger gold bead that won't slip over the small gold bead. This is the second bead you put on the pin.
d. A large blue semi precious bead with a hole drilled through it from top to bottom. This is called a focal bead because it is larger than most beads, is especially attractive, and may have an unusual shape. This is the last bead you put on the pin.
e. A jump ring (a simple small metal ring usually used in jewelry making to attach one part of a jewelry piece to another part). Slip the tip of the end pin, over which you just finished slipping the focal point bead, through the jump ring.
f. Jewelry pliers. Use jewelry pliers to bend the end of the pin through the jump ring and close it tight.
g. Open the jump ring with the pliers and slip it over the key ring. Close the jump ring carefully.
h. Jewelry glue. Using a toothpick or the tip of a pin, apply a small piece of jewelry glue to hold the jump ring together so it doesn't come apart accidentally. Also put a small piece of jewelry glue at the joint where the tip of the pin was folded over the jump pin, so that circle won't accidentally open.
i. Hang the ring up for a day or two so the glue dries well.

 ◦ 2
 This bracelet key ring can be worn around the wrist or carried in a pocket or handbag

BRACELET KEY RING
This is an alternative to wearing a key on a chain around your neck. It is best to use this method to hold a small key ring and a small key.
a. The easiest way to make a bracelet is to use stretchable jewelry "wire". It is especially useful for bracelets that can slip over the wrist and then come to shape so they won't slip off easily by themselves.
b. This bracelet is made with alphabet beads to resemble a baby bracelet. It is easy to personalize for a mother or grandmother. Of course any other type of bead could be used, but remember that very large beads can be uncomfortable to wear on your wrist.
c. Be sure to put the bracelet through the key ring before finishing the bracelet. Otherwise you will have to make a bracelet with a clasp so that you can slip the ring over the clasp and then close the bracelet.
d. It isn't necessary for this kind of key ring to actually be worn on a wrist. It also works well in a purse or pocket, because the bracelet hoop is easy to find by sight or touch.

 ◦ 3
 Key ring made with beads on a changeable pendant post

FINISHED KEY RING RING MADE WITH BEADS ON A CHANGEABLE PENDANT POST
a. The basis for making this key ring is a changeable pendant post. These are essentially intended to make easy pendants but the elongated bead design makes it easy to grasp and works well with a key ring.
b. A changeable pendant post is a thick pin with a fixed metal bead on one end and a screw off metal bead on the other. The screw off bead has a hoop attached to slip over a chain or key ring.
c. Select three to six beads to slip over the middle pin. Arrange them in an order that pleases you. Note that these beads must have larger than average holes through them so they can slip over the pin.
d. When all the beads have been placed, screw the final metal bead on fairly tightly and slip it over the key ring.

 ◦ 4
 Unscrew the end of the pendant post in order to change the beads

One of the best features of this kind of key ring is that you can rearrange the beads and/or change the beads to suit your various outfits or taste.


What will decreasing a telescope's eyepiece focal length?
The magnification of the telescope image is(focal length of the objective) divided by (focal length of the eyepiece).The focal length of the objective is fixed.Decreasing the focal length of the eyepiece increases the magnification of the image.(But it also makes the image dimmer.)
Which lens in a refracting telescope has a shorter focal length?
The eyepiece will have a shorter focal length than the objective lens has.
If a telescope has an objective with a focal length of 50 centimeters and an eyepiece with a focal length of 25 millimeter what will be the magnification?
20
What happens if you decrease a telescopes eyepiece focal length?
The magnification of the telescope image is(focal length of the objective) divided by (focal length of the eyepiece).The focal length of the objective is fixed.Decreasing the focal length of the eyepiece increases the magnification of the image.(But it also makes the image dimmer.)
How is magnifying power of telescope and a microscope are a affected by increasing the focal length of their objectives?
The magnification of a telescope M is the the focal length of the objective Fo over the focal length of the eyepiece Fe so increasing the focal length of the objective increases the magnification. The magnification of a microscope M is approximately tube length L/Fo x 25/Fe. Therefore increasing the focal length of the objective reduces the magnification.
What is the power of the eyepiece?
The magnification, or power, at which a telescope is operating is a function of the focal length of the telescope's main (objective) lens (or primary mirror) and the focal length of the eyepiece employed.
If a telescope with an objective lens of ten feet focal length is used with an eye piece of one quarter inch focal length what would the resulting magnification be?
The magnification (MA) equals the focal length of the objective lens (fo) divided by the focal length of the eyepiece (fe), which is this: MA = fo / fe = 10 feet / .25 inches = 120 inches / .25 inches = 480 A link to the Wikipedia article on magnification is included.
What would be the effect on magnification to increase the focal length of microscope and telescope?
The focal length of a telescope is directly related to the magnification in that the longer the focal length, the more magnification you get from the telsceope. How the focal length of a telescope relates to the length of the telescope itself depends on the design of the telescope. In a refracting telescope, the focal length is approximately the length of the telescope. In a reflecting telescope, the focal length is roughly two time the length of the telescope.
What is the magnification of a reflecting telescope with an eyepiece of focal length 25 mm and an objective lens of focal length 2000 mm?
That's 80 power.
What is the formula for light gathering power for telescopes?
For visual observation: Magnification = (Focal Length of Objective Lens) divided by (Focal Length of Eyepiece) (They have to be measured in the same units.) For prime-focus photography: (One focal-length of the Objective Lens on the film) = (one radian in the sky)
The magnification of a telescope is changed by changing the?
The magnification of a telescope is the ratio of the effective focal length of the objective to the focal length of the eyepiece. For example, a small telescope's objective may have a focal length of 800mm. When an eyepiece with a focal length of 25mm is used, the magnification is 800/25 = 32. The term "effective focal length" refers to the focal length of the objective as affected by any "focal extender". Many telescopes are designed to have a short total size, but high power, by "folding" the optical path. A mirror-type objective with a focal length of perhaps 800mm is coupled with a smaller curved mirror that intercepts the last 200mm and extends it to 800mm, a 4x extension, so that the effective focal length of that objective is 3200mm. Use that with a 25mm eyepiece and the magnification is 3200/25 = 128. By the way, if a telescope is smaller than you are, it is seldom much use to view using a magnification greater than 50 to 100. Most objects are best viewed at relatively low powers such as 30 or so.
The magnification of a telescope is changed by changing the what?
The magnification of a telescope is the ratio of the effective focal length of the objective to the focal length of the eyepiece. For example, a small telescope's objective may have a focal length of 800mm. When an eyepiece with a focal length of 25mm is used, the magnification is 800/25 = 32. The term "effective focal length" refers to the focal length of the objective as affected by any "focal extender". Many telescopes are designed to have a short total size, but high power, by "folding" the optical path. A mirror-type objective with a focal length of perhaps 800mm is coupled with a smaller curved mirror that intercepts the last 200mm and extends it to 800mm, a 4x extension, so that the effective focal length of that objective is 3200mm. Use that with a 25mm eyepiece and the magnification is 3200/25 = 128. By the way, if a telescope is smaller than you are, it is seldom much use to view using a magnification greater than 50 to 100. Most objects are best viewed at relatively low powers such as 30 or so.
