Can barcode scanners read barcodes displayed on an iPhone or other smartphones? Why or why not?
Laser based scanners, which are still very common because they are extremely inexpensive, can not read the image of a barcode displayed on a smartphone screen. A laser based scanner uses a tiny motor to sweep a low powered laser across the black and white spaces of a traditional printed barcode. At the same time, the laser is being modulated into pulses of light of varying lengths, not completely unlike Morse code), determined by the quantity and thickness of the white spaces separating the black lines. A simple photodiode measures the pulses and a computer applies an algorithm to determine the code was correctly read, and then sends the barcode like very fast keystrokes. 2D (two dimensional) scanners use a small camera that instantly records the image, which is backlit (the very thing that 'blinds' traditional scanners) and sends the verified output to whatever POS or computer it is connected to. A 2D scanner is traditionally lit, if necessary, by ordinary red LEDs and some do incorporate a laser generated aiming pattern and that is really just to assist the operator.
How is shadow formed?
A shadow is cast on the side of the object that is furthest from the light source. The proximity of the object creating the shadow to the light source determines the relative size of the shadow. As an object moves further from a light source, the shadow becomes smaller, and as an object moves closer, the shadow becomes larger. The angle of the light source determines the length of the shadow. At sunrise and sunset, the low angle of the sun creates the longest shadows. The shortest shadows are formed at noon when the sun is highest in the sky.Most shadows are made up of the umbra and the penumbra. All light is blocked by an opaque object in the umbra. In the penumbra only part of the light is blocked and is an area of partial darkness. For a point source, such as a flashlight shining through a pinhole in a sheet of paper, the shadow that forms is entirely umbra with no penumbra.
What is the best way to stay healthy?
1. Wake Up Early"The early morning has gold in its mouth," said Benjamin Franklin.You would have read this advice a zillion times, but trust me it works, it really does.One very significant benefit of waking up early is reduced stress level. When you rise early, it eliminates the need to rush in the morning. You can then start your day on an optimistic note and such positivity often stays with you throughout the day.Also When you are in harmony with the nature's cycle, nature will bless you with good health.2. Move your BodyKeep yourself physically active. You can play a sport, go for running , do some weight lifting , practice asanas ,dance or whatever you like.Sitting for prolonged hours has tremendous ill-effects for health. Try with small things like taking up stairs instead of elevator, walk instead of taking a car and slowly increase your fitness goals and work on them.3. Eat clean and healthyKeeping yourself physically active doesn't give you license to eat whatever comes on your plate.Be observant of what you are eating, our bodies are one of the most complex and amazing machines. Don't mess with it.Eat a balanced diet and try to stay away from junk.Include lot of veggies in your diet. And eat good amount of raw salad along with your meals.4. Calm down your inner turbulenceMost of our worries and inhibitions originate within our minds.Try to reduce stress in your life. Its easier said than done, but mindfulness and meditation come to rescue. Start practicing meditation for 5 minutes a day.Moreover start living in present and stop worrying about unnecessary things.5-5-5 rule works like a charm, whenever worried about something , think if this will matter in next 5 minutes, 5 months or 5 years.5. Drink loads of waterKeep a water bottle with you all the time during travel , during office hours and at home.Make sure you finish 2-3 litres of water each day. Water flushes toxins out of your body.6. Sleep wellOur body's healing process happens during sleep, so if we don't take proper sleep, we are messing up with the process.Try to sleep 6-8 hours depending on your body. Moreover keep virtual world away from you before going to bed.Stay happy and stay healthy :)