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Kitchen Bulb: Newsletter Challenge (10/25/05)

Posted October 25, 2005 7:00 AM

The question as it appears in the 10/25 edition of Specs & Techs from GlobalSpec:

You're in a friend's kitchen, where there's only a single, bright, high-wattage light bulb and no windows. (Rather bleak!) Your friend wonders what the bulb's wattage is (he wants to be prepared for when the bulb needs replacement). He remarks he'd like to read the power directly off the bulb but it's too bright (even when squinting) and turning off the light, well, kind of makes it a bit dark in the room... You say to him "I bet you I can do it without leaving this room, and I don't have my sunglasses with me and have no idea if you have a flashlight in here." He says, "No way." You say, "Way." What do you do?

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#1

Bathing in the afterglow

10/25/2005 7:57 AM

Stare at the bulb for a few seconds, get your friend to turn off the light, close your eyes and read the figure printed on the bulb from the imprint on your retina.

The image will be "negative" (black for white, colours swapped) and only last a few seconds. Repeated blinking can reinforce the image.

It's caused by overloading the rods and cones temporarily and causing a form of temporary threshold shift, percieved by us as an image imprint.

Just don't get the bit of the bulb with the writing on in the centre of your vision - you get a white out. I know coz I've just tried! LOL

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#13
In reply to #1

Re:Bathing in the afterglow

10/26/2005 8:15 AM

Blink your eyes open and shut while facing the bulb at a convenient viewing distance. The momentary exposure decreases the white-out, and one can often rememmber what was on the bulb (especially when the afterimage cues the brain) with even a fraction of a second viewing time.

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#2

No Retina Damage

10/25/2005 9:21 AM

Have your friend turn off the light and let the bulb cool. Cover the bulb with both hands or with dark paper or cloth. Leave only the tip of the bulb exposed where the wattage is printed. Position your eyes at a slight angle to the most direct beam. have your friend turn on the light and read the wattage. The amount of light from the small exposed area of the bulb will be minimal and the indirect light will not burn your retina.

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#3

KItchen light

10/25/2005 11:00 AM

Perfect opportunity to explore the properties of a pinhole lense! Take a dark piece of card or paper, and prick a tiny hole in the centre (a pinprick will do fine). When this is held at a distance under the light bulb (assuming the bulb is exposed) it will produce an upside-down image of the text printed on the glass bulb. hold your hand under tha card to view the image. The quality depends on the orientation of the pinhole to the light source. Try it out, it's pretty cool.......:-)

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#14
In reply to #3

Re:KItchen light

10/26/2005 8:22 AM

Since you have paper, pull out your chalk and make a rubbing of the print on the bulb. Or take some mylar ("magic mending") tape from the kitchen drawer and momentarily put in contact with the print. Use a reflection off the tape surface to read the imprint.

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#4

reading info

10/25/2005 11:21 AM

I would take any piece of clothing-that will let light through- and hold it up to the light it will act like a filter so that you can see the writing-do not need sunglasses - elementary dear watt-son

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#5

Pinhole lense

10/25/2005 11:45 AM

On second thoughts, I realise I'm talking absolute rubbish!!! It's a normal lense you need to use, not a pinhole!My mistake, it's been a long day!!!!

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#6
In reply to #5

Re:Pinhole lense

10/25/2005 2:56 PM

Place a glass filled with water a short distance under the light. Now look down at the glass from above for the refelction of the bulb off the surface of the water. Remember the image will be reversed (mirrored), so don't order a 001 watt bulb. Don't ask me how I know.

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#7

flick your bic

10/25/2005 3:27 PM

Just another case where being a smoker comes in handy. Simply turn the light off, flick your bic (lighter for those non-smokers) and read the wattage from the bulb. Gather cool points if you don't burn the friends house down.

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#17
In reply to #7

Re:flick your bic

10/27/2005 1:20 PM

What are the other cases?

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#20
In reply to #17

Re:flick your bic

11/29/2005 12:57 PM

see question "how to start a fire" 11/22/05 a bic here would also work wonders

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#21
In reply to #20

Re:flick your bic

11/29/2005 1:06 PM

Fair enough.

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#8

Pinhole lens and foolish friends

10/25/2005 7:10 PM

my thoughts were along the line of the dimming filter (cloth or pinhole lens are good examples) and I would have chosen a piece of paper. Paper will diffuse the light enough to look at it, and if you put the paper up against the bottom of the light, the shadow cast from the lettering will still show on the paper. Of course, you could burn the cloth/paper in the process, so I would use the pinhole (reduced aperature) lens idea. It lets less light in and for bright applications, provides excellent focus. Check wikipedia for an explanation. I just have one question, how is your friend going to change the light bulb in a room too dark to see anything? Pennywise and pound foolish if you ask me.

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#9

"Hand" made light filter

10/25/2005 7:14 PM

By creating a "telescope" with your hands with the smallest appeture needed to see the label on the bulb the bright parts of the bulb are filtered and the bulb label can be identified. The lettering on the bulb makes that part a little less bright. Its similar to primative eskimo sunglasses.

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#10

Kitchen Bulb

10/25/2005 10:29 PM

First, take a bottle or two beer and had a cheer with your friend. Drink the beer first. Enjoy it. With the empty beer bottle use it to protect the bright light from the bulb and you can read power directly from the bulb. I am sure you guy's keep a lot of beer in your ice box.

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#11

Light Bulb Wattage

10/25/2005 10:50 PM

Okay guys, this one is too simple. The key is, the statement that: "You're in a friend's kitchen,...". What appliance is in every kitchen? A range of some kind (electric or gas). An electric or gas element/burner will emit some light when on. Simply unscrew the light bulb in question and place it next to the element/burner and read the wattage. ! ...Did I win?

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#12
In reply to #11

Re:Light Bulb Wattage

10/25/2005 10:59 PM

...Another solution: Open the refrigerator door. Assuming the bulb inside the refrigerator is good, unscrew the lightbulb in question and take near the refrigerator to read the wattage.

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#15
In reply to #12

Re:Light Bulb Wattage

10/26/2005 11:01 PM

Get a couple of bottles of whiskey, a sledge hammer, and a sheet of glass. After having some whiskey, knock a hole in the wall and make a window. Turn off the light and take a look. (No more bleak kitchen. Yay!) (What's with all the eye related questions anyway?)

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#16
In reply to #15

Re:Light Bulb Wattage

10/27/2005 1:31 AM

Yeah, That is a good idea. Good suggestion. I agree with it.

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#18

And the Answer is...

11/02/2005 11:42 AM

As written in the 11/01 issue of Specs & Techs from GlobalSpec:

You walk over to the cupboard, take down a water glass and put some water in it. You then stand on a chair, get close to the light bulb and look at the bulb's reflection off the surface of the water in the glass. You can then easily read what's printed on the bulb. The amount of light reflected off the water's surface is only a few percent, which drastically cuts the light intensity to your eyes and makes it possible to read the bulb. Of course, you could do the same thing by breaking one of the windows in his other rooms and using a piece of glass to direct "front surface reflection" into your eyes (front surface reflection from glass is similarly a few percent), but that technique is a bit more drafty.

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#19

Its all thermodynamics

11/13/2005 9:28 PM

You are in a kitchen, so there is most likely an oven thermometer of some sort. This is also a fridge. Place lightbulb and themometer in fridge. (Plug the lightbulb in by your favorite method.) Unplug the fridge. With your kitchen clock, and above stated thermometer, record the temp increase over time. Using your knowledge of watts and heating of air etc, calculate the rating of the bulb. If you don't want to do a lot of calculations, then use a bulb of known wattage to monitor the temp increase. Then, inset mystery bulb and compare temp change. Alternatively, if one has a reference bulb, (say from the fridge, stove, fume hood etc) then plug it in and start wrapping paper towels around the bulb. When no more light is visible - stop. Now take your mystery bulb and turn it on. Wrap with paper towels. Compare the number of wraps required for the mystery bulb, and for the reference bulb. Using the appropriate math (something in there to the 4th power) figure out wattage of mystery bulb. Even more fun would be to wrap a reference bulb and mystery bulb with paper towels and to time how long it takes each assembly to catch on fire. Relative times can be used to calculate wattages. Lastly, how about taking a pot of water and submersing the bulb in the water. Of course, leave the live electrical connection dry. Time how long it takes to bring the water to a boil. Either do the math - knowing the heat capacity of water, calories etc. to figure out wattage, or put the same amount of water in your xxx watt microwave oven, and time how long it takes for the water to boil. Do the necessary math to calculate wattage of bulb.

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