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Which will burn faster "A4 paper, newspaper or black paper" if we use magnifying glass and the light of the sun? |
Anne |
28/6/2015 |
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| Q2: |
What are near and far points? How they are to be controlled? |
Upplapu Srinivasa raju |
20/8/2010 |
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| Q3: |
how long does it take to heat up a managifying glass |
cayla |
8/5/2010 |
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| Q4: |
The heat from sun light shadow rays that pass through a lens,when it burns a carbon paper and store watts of energy if it is directed to analogue video convert ADC,will galatic picture be show on T.V serial video input? |
Nzewi uchenna osita |
13/4/2010 |
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| Q5: |
Can the light that is focused at the focal length of the Fresnel lens be reflected off a flat mirror to another point or should you use a parabolic mirror shape? |
Drock |
27/10/2009 |
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| Q6: |
what material will best absorb or reflect the sun rays through a magnifying glass? |
Sue |
16/4/2009 |
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| Q7: |
can heat from human body burn a paper...? i have read such a incident once in a news paper..? if or if not please explain with a example..? |
karthi kumar |
13/3/2009 |
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| Q8: |
Can you burn paper with a magnifying glass and a 100 watt light bulb ?? |
Jon Brimus |
20/8/2008 |
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| Q9: |
Why is it unlikely that user would see image of magnifying glass clearly if his eye was almost touching lens? |
Joyce |
3/5/2008 |
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| Q10: |
Transmitting the light from a candle, a flashlight and the sun, how long would a magnifying glass take to burn a piece of paper. Exact time please. |
Kevion |
29/3/2008 |
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The light from a flashlight and a candle is too weak to burn a paper, for Sun it depends on the time of the day, thickness of paper, ambient temperature etc. normally sharply focused image of sun at 33 deg C at 13:00 hours took around 7 seconds to burn a hole in 60 gsm paper, while 70 gsm white photocopy paper took 11 seconds to burn a hole. |
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| Q11: |
I want a magnfying glass for field application for producing hot air for drying. Please give the Indian dealers address who sell the magni glass. |
Prof. Eswarappa |
4/1/2008 |
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Please try searching on ebay india, sulekhab2b.com, indiamart.com and shop.rediff.com for getting the name of manufacturers or deals in magnifying glasses |
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| Q12: |
What type of magnifying glass sould be used for solar applications?. where is it available ? and how expensive is it. |
K. Venkatachalapahy |
28/12/2007 |
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Convex type should be used (magnifying glasses are convex type by default), all kinds of focal lengths are available but the higher the better. It is available at all stationary shops and should cost more than Rs. 40-120 ( $1-3) |
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| Q13: |
How much does it cost all of physics simulations . Can you let me to change the text from english to Turkish so I useit. I am a physics teacher. |
Lütfü KURT |
9/11/2007 |
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The cost of the animation is given in the downloadable files pricelist in the download section, but changing the text from english to turkish is not possible. |
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| Q14: |
how far from the mirror should the paper to be ignited? |
jessa |
26/7/2007 |
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It should be equal to the focal length, in general terms far enough to generate a small circle or pinpoint of the light on the paper |
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| Q15: |
With my back to the sun for an hour playing backgammon, while wearing black sunglasses at the beach I managed to burn my nose tip so severely it took two to three weeks to heal. One year later, Basal Cell Carcinoma in that very spot. Cause? Sunglass |
Maureen |
17/5/2007 |
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BCC is commonly found on the nose and eyelid, and the mostly in fair skinned people who have less melanin, and freckle or burn rather than tan. Sunglasses may not have caused this as high energy UVB, the primary agent responsible for sunburns can’t penetrate glass, also dark glasses cannot focus light on to a point. In addition, BCC grows slowly and is painless but can be caused by radiation damage. So most likely,the sensitive skin of nose was damaged due to direct UVB exposure not sunglasses. |
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| Q16: |
How hot does the focal point of a 4 inch Dia. magnifying glass get?? |
MOnkey |
17/5/2007 |
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Do you mean temperature? This is found by calculation rather than measurement, will need to calculate energy , sun's power on the surface of the earth is about 1200 W/m^2, calculate area of lens and sunrays intercepted. Aberrations causing defocusing of the lens (removable by using compound lens), emissivity of the surface and the conductivity need to be known, also account for 4% Fresnel reflection loss off the surface of the magnifying glass. Use Stefan-Boltzmann law to calculate temperature. |
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| Q17: |
what kind of energy are involved using a magnifying glass and a piece of paper |
sumi |
17/4/2007 |
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Lets include Sun also ;). Visible and IR radiation from sun travel to hand held magnifying glass – some absorbed by and rest pass through magnifying glass and are focused on a paper that burns. Sun to magnifying glass – thermal energy, KE (temperature). Hand holding lens – muscular energy, paper burning means bond breaking and temperature rise – thermal, potential and kinetic energy. One could go on and on – like IR radiations and air molecule interaction, energy of smoke … |
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| Q18: |
A computer monitor screen appears convex. If I cut the glass screens of two monitors and place them back to back would this work as a magnifying glass? |
Paul Kontominas |
30/3/2007 |
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Theoretically, it will, but since the glass plate’s radius of curvature is very high, the magnification will be very low, it will serve as a weak lens. |
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| Q19: |
What is the focus tempeture of a Frasnel lens,is hotter then the normal magnifying lens?If it is by how much? |
George |
18/3/2007 |
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The Fresnel lens is a powerful concentrator as it captures 85% of incident light compared to 20% for ordinary lens. It can concentrate 20 times to 400 times depending on its type and is used in solar furnaces. It produces extremely high temperatures in a small area. For ambient temperature of sunrays of 25 deg C, it can produce a temperature of 500 deg C (M =20). A medium temperature solar thermal concentrator produces heat around 100~250 deg C while a high one will around 1500–1800 deg C. |
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| Q20: |
What's the time? |
Tarqin |
14/3/2007 |
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The time taken for burning depends on a) material b) sharpness of focus c) ambient temperature d) angle of the Sun e) color of the material, for example in our experiment a blue carbon paper with sharply focussed image of sun at 33 deg C at 13:00 hours took around 7 seconds to burn a hole, while 70 gsm white photocopy paper took 11 seconds to burn a hole. |
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| Q21: |
How did the magnifying glass originated? |
Josefina B. Dela Rosa |
13/3/2007 |
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Their origination lies in a blurry and unrecorded past, probably transparent crystals with a thicker middle part were discovered to magnify objects, or burn materials using Sun. These were known as “burning glasses”; Greeks in 448 BC and Romans in 1st AD have recorded their use. Nero in AD 50 used emerald for watching games. In 1st Century AD glass was invented by Romans and used as a lens. In 1268, Roger Bacon, wrote the first scientific literature describing them for vision correction. |
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| Q22: |
If you place a magnifying glass close to an object, would it still burn or does the distance from the object make a difference? |
Mike Howse |
7/3/2007 |
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Distance makes a difference, it has to be at a its focal length to focus all rays onto a single point to achieve quick burning, at any other distance the rays will be diffused and the burning may not occur or if it occurs will take a long time. |
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| Q23: |
how does magnifying glass works on burning paper, leaf and plastic |
raynamay |
7/1/2007 |
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Magnifying glass can focus sun's rays onto a point and can produce intense heat, about 1,000 watts per square meter of Sun's energy filtered through atmosphere reaches us, imagine focusing half of that onto a few mm of space and you can burn a leaf of paper with it, thin plastic may burn but the amount of heat and time required to burn thicker plastics like a water bottle may be more, refer burning with magnifying glass animation on our site. |
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| Q24: |
what is the principal of working of pinhole camera is it reflection of light or refraction of light |
bhaumik |
15/9/2006 |
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Neither it is reflection nor refraction; it is the rectilinear propagation of light that is responsible for formation of image in a pinhole camera |
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| Q25: |
About how long does it take colored paper to burn using a magnifying glass? For instance, using red, green, or blue. |
Miguel |
14/3/2006 |
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Depending on the weather conditions, intensity of sunlight, focal length of convex lens and thickness of paper it takes from less than 10 seconds to upto 30 seconds burn a hole in the black paper, we have not been able to experiment out with other colors but will do that soon and publish the findings, but if you could do that we will publish yours with credits. |
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| Q26: |
Which color paper burns the fastest with a magnifying glass and why? |
kreesha |
26/2/2006 |
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Dark colors will burn faster than light colors; Black will burn the fastest, the paper appears black as it is absorbs the light radiations (light energy ) completely while other colors reflect back some part of light , the energy of the absorbed radiation is partly used for raising its temperature and partly used for emitting longer wavelength infra-red radiation, since it absorbs more energy its temperature rises fastest and it burns fastest. |
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