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Showing posts from February, 2021

How do barcodes work?

  How do barcodes work?           Barcodes are a machine-readable way of writing letters and numbers. A laser is shone onto the barcode and the reflected light can be interpreted by the barcode reader. There are many types of barcodes, but the ones most commonly found in supermarkets use a row of lines of different widths. The different widths represent different numbers.           In the some Country many items are coded with a GTIN – Global Trade Item Number. This allows the manufacturer to print the barcode on the packages. The numbers are unique to that item. The barcode only has a number, but no product information. That is held in a database which the retailer can access at the point of sale. It also means that shops can set their own prices and change them easily.

Can a compass work underground?

  The compass app on your phone probably won’t work because it depend on radio signals that are easily blocked by rock or water, but for a compass with a wobbly needle, it just depends on how far underground. A compass works because its magnetised needle lines up with the magnetic field that runs between Earth’s north and south poles, and that field is just as powerful if you go down a mineshaft or into the depths of the ocean. But the field is created by swirling molten iron in Earth’s core, and if you could drill that far down, you’d find your magnetic needle going haywire.

How are light trails captured? how to capture car light trails?

          Light trails are a colourful and creative effect that photographers can capture by employing long-exposure shooting on their camera. The basic principle of light trail creation is that by manually dropping a camera’s shutter speed to a very low level, light is captured by the sensor over an artificially long period of time, with every passing vehicle having its lights tracked and recorded over the visible distance of the road.           To take a shot like this one, find a roadside vantage point in which no other moving objects are visible other than the passing vehicles. Second, mount the camera on a tripod, as stability is key while shooting long-exposure imagery. This is because if there is any camera shake while the unit’s shutter is open, then the captured light will lose its direction and smudge across the entire image. Next select the shutter priority setting on the DSLR camera and drop the shutter speed to the desired level , this means at least a 30 second exposure.

How do Venus flytraps work?

            Venus flytraps tend to grow in boggy soil that’s low in nutrients, hence they need to find another source of food to sustain them, namely insects that happen to land on their leaves. These leaves are about eight to 15cm long and are ‘hinged’ along the midline with spiny teeth around the edges.               The folding and trapping action is triggered by pressure on six sensitive hairs that, when simulated will snap the leaf shut in about half a second, although the actual nature of the action is still debated. As well as these sensitive hairs, the leaf also has glands on its surface that secrete a sap which digests the insect’s body. This process takes about ten days, after which the leaf reopens.