Two thin lenses of power `+ 3 D and - 1 D` are held contact with each other. Focal length of the combination is :

Two thin lenses of power `+ 3 D and - 1 D` are held contact with each other. Focal length of the combination is :
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Two thin lenses of power `+ 3 D and - 1 D` are held contact with each other. Focal length of the combination is :
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Pick up the correct statement from the following: (A) The power of a lens is the reciprocal of its focal length (B) The unit of power of the lens is Diopter (C) The power of two or more thin lenses in contact is the power of the combination of the lenses (D) All the above

Description : Pick up the correct statement from the following:  (A) The power of a lens is the reciprocal of its focal length  (B) The unit of power of the lens is Diopter  (C) The power of two or more thin lenses in contact is the power of the combination of the  lenses  (D) All the above 

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Two thin lenses of focal lengths 15 cm and 30 cm resepectively are kept in contact with each other. What is the power of the combined system?

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Two concave lenses of 60 cm focal length are cemented on either side of a convex lens of 15 cm focal length. The focal length of the combination is (A) 10 cm (B) 20 cm (C) 30 cm (D) 40 cm

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A converging thin lens has a focal length of 27 centimeters. An object is placed 9 centimeters from the lens. Where is the image of this object formed?

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Pick up the correct statement from the following: (A) Spherical aberration may be reduced by diminishing the aperture (B) Spherical aberration may be minimised by replacing the single lens by a combination of the lenses (C) In telescope objectives, a combination of convex lens and concave lens is used (D) All the above

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A student focuses the image of a candle flame, placed at about 2 m from a convex lens of focal length 10 cm, on a screen. After that he moves gradually the flame towards the lens and each time focuses its image on the screen. (a) In which direction does he move the lens to focus the flame on the screen? (b) What happens to the size of the image of the flame formed on the screen? (c) What difference is seen in the intensity (brightness) of the image of the flame on the screen? (d) What is seen on the screen when the flame is very close (at about 5 cm) to the lens?

Description : A student focuses the image of a candle flame, placed at about 2 m from a convex lens of focal length 10 cm, on a screen. After that he moves gradually the flame towards the lens and each time focuses its ... d) What is seen on the screen when the flame is very close (at about 5 cm) to the lens?

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If I wanted to try contact lenses, could I just order some on Amazon, using the dioptric values of my current glasses?

Description : If I wanted to try contact lenses, could I just order some on Amazon, using the dioptric values of my current glasses?

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Description : How to know if contact lenses are expired?

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My friend wore contact lenses for 8 months. Is this safe?

Description : My friend wore contact lenses for 8 months. Is this safe?

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Do you have a trick for putting in and taking out contact lenses?

Description : Do you have a trick for putting in and taking out contact lenses?

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What does the designation medium or high mean on contact lenses?

Description : What does the designation medium or high mean on contact lenses?

Last Answer : answer:Bifocal contact lenses generally contain one additional number which is the add power. A special field will be given for this number. Notes 1. A contact lens prescription is not the same as ... correct for it by changing the power of the lens. Still Have Questions? Email : [email protected]

Where do you buy your contact lenses?

Description : Where do you buy your contact lenses?

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Can I use contact lenses that have frozen (and then thawed, perhaps multiple times)?

Description : Can I use contact lenses that have frozen (and then thawed, perhaps multiple times)?

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Why have my contact lenses been bothering me so much lately?

Description : Why have my contact lenses been bothering me so much lately?

Last Answer : How long do you have them in each day?

Where can I get contact lenses for a Flapjack Costume?

Description : Where can I get contact lenses for a Flapjack Costume?

Last Answer : Whatever you do be careful to avoid the cheap crap available from party shops and such. People have ended up with some really nasty eye infections that way. Putting your eyesight in danger seems ... . Go to an Optlamologist and get a recommendation for a reliable local source for specialty lenses.

What happens if you wear your 14-day contact lenses longer than 14 days?

Description : What happens if you wear your 14-day contact lenses longer than 14 days?

Last Answer : Infection becomes a much more serious possibility. In a worst case, blindness could ensue.

What is the cheapest way to buy contact lenses (Acuvue Oasys)?

Description : What is the cheapest way to buy contact lenses (Acuvue Oasys)?

Last Answer : Yes! I wear them and have researched the cost. The cheapest place to get them is Costco, hands-down.

Do you have a preferred brand of contact lenses that you would recommend?

Description : Do you have a preferred brand of contact lenses that you would recommend?

Last Answer : The most comfortable contacts I've ever worn are Acuvue2 - haven't tried the oasys, but kind of want to. When I first put the Acuvue2s in, I can not feel my contacts whatsoever and would probably forget ... start to irritate my eyes by then. New, though, I love them and never have to use eye drops.

Polarized contact lenses?

Description : Polarized contact lenses?

Last Answer : According to Google, no. Probably because if someone were to make them, it would take about 10 seconds to realize that they can't move around on the eye or the polarization wouldn't work. Because ... 't work well. Not saying its impossible, just not as easy popping polarized lenses in your eyes.

What are the harmful aspects of contact lenses ? ?

Description : What are the harmful aspects of contact lenses ? ?

Last Answer : The biggest risk of using contact lenses in the eye is infection. The most serious of the eye infections is keratitis. This infection can be caused by bacteria and other germs. Studies have shown ... eyelids are closed while wearing lenses. Due to this, the eyes become weak in dealing with germs.

What kind of eye problems can be caused by using contact lenses ? What are the rules for wearing it ?

Description : What kind of eye problems can be caused by using contact lenses ? What are the rules for wearing it ?

Last Answer : Beauty enhancement or need , because whatever it is , the use of contact lenses is increasing day by day. Women wear contact lenses to make themselves attractive in various programs or events. Many again wear ... place. -Use a separate box for each contact lens and make sure it is full of solution.

R = -0.25 Into 15 Degree L = -0.25 Into 175 Degree Which would be better to use ? Spectacles or contact lenses ?

Description : R = -0.25 Into 15 Degree L = -0.25 Into 175 Degree Which would be better to use ? Spectacles or contact lenses ?

Last Answer : If you want to use contact lenses, but it is very useful, it is important to take some precautions. Each contact lens has a specific expiration date. It can be 3 months-6 months-1 year. ... cheap quality products that hurt your eyes while keeping an eye on the price. Learn more about other things

Do you wear glasses / contact lenses?

Description : Not yet, but I should wear glasses.

Last Answer : I don't use any of them, luckily I don't have any problems with my eyes.

contact lenses or eyeglasses?

Description : en dare not touch my eyes ....

Last Answer : I was wearing glasses

Are glasses or contact lenses cheaper?

Description : Is it cheaper to buy glasses or contact lenses?

Last Answer : Probably glasses

Will glasses or contact lenses come out cheaper?

Description : What comes out cheaper?

Last Answer : Ultimately, glasses (unless you mechanically destroy them) - contact lenses are only for a limited time.

Are contact lenses instead of glasses?

Description : Why do people wear contact lenses? Is it a replacement for glasses?

Last Answer : Yes, they replace the function of glasses, that is, they are instead of glasses.

Avoid Dry Eyes With These Contact Lenses?

Description : Avoid Dry Eyes With These Contact Lenses?

Last Answer : One of the most uncomfortable sensations anyone can experienceis dry eyes. If you don't wear contact lenses, you might have haddo deal with dry eyes before, but not to the extent of those who ... ?Simply because there is not as much oxygen reaching your eyes. Whenyou put your contact lenses in

How to Know When Contact Lenses Are Not for You?

Description : How to Know When Contact Lenses Are Not for You?

Last Answer : While contact lenses are a great option for correcting vision,they are not necessarily the right option for everyone. Dependingon your eyes and your lifestyle, you may find that you areperfectly ... certain vision conditions, such aspresbyopia, you may need very specialized contact lenses, and itwi

Do I need a copy of my prescription to order contact lenses online?

Description : Do I need a copy of my prescription to order contact lenses online?

Last Answer : It's helpful if you have a copy of your prescription. This can help you determine what type of contacts you need.

Should I get contact lenses or LASIK?

Description : Should I get contact lenses or LASIK?

Last Answer : This would depend on personal desire. Contact lenses are a headache to deal with, but sugery costs thousands and is usually not covered by insurance.

Where can I buy colored contact lenses online for cheap?

Description : Where can I buy colored contact lenses online for cheap?

Last Answer : The best place with the highest rating for a contact lenses online website is coloredcontacts.com. You will find contact lenses there for 14.95 and ever possibly a free offer for a pair.

Do you have to go to an eye doctor to get prescription eyeglasses if you already have a prescription for contact lenses?

Description : Do you have to go to an eye doctor to get prescription eyeglasses if you already have a prescription for contact lenses?

Last Answer : It depends on the eyeglass company as to whether they'll accept your contact lens prescription or not, so just ask them. That said, some eye doctors make slight modifications to your prescription for contact lenses, so it may be best to go back for a separate eyeglass prescription anyway.