MRI Scanner. How stuff works

MRI Scanner is the Medical Imaging device used to image the soft parts of the body especially the Brain. Magnetic Resonance Imaging or MRI is the technique used in MRI scanner to provide the detailed structure of the brain. Unlike CT (Computed Tomography) scanning, MRI uses no ionizing radiation but uses powerful magnetic field to align the nuclear magnetization of hydrogen atoms in the water content of the body. Diseased tissue, such as tumors, can be detected because the protons in different tissues return to their equilibrium state at different rates. By changing the parameters on the scanner ,this effect is used to create contrast between different types of body tissue.Patients with some metal implants, cochlear implants, and cardiac pacemakers are prevented from having an MRI scan due to effects of the strong magnetic field and powerful radio frequency pulses.

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Mains Tester. How Stuff Works

The common AC tester is the simplest form of tool to test the presence of AC in the mains wiring. The Screwdriver type AC tester has a Neon lamp inside which glows when the current passes from the mains wiring to the ground through the user’s body. It uses the stray capacitance of the body to complete the circuit.
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Bar code Reader. How Stuff Works

Barcode is a label with white and black stripes to denote the specification of a product. It is generally used to represent the products features, prize, quantity etc in coded form. This is meant to avoid malpractices during billing and sale. To retrieve the data from the bar code label, a barcode reader is used which is now common in commercial establishments like Super markets. The barcode reader is an electronic device connected to a computer. Its face has a light source either Laser or Infrared. The light reflects back from the barcode and the Photodiode in the reader translates the optical impulses into the corresponding electric signals. The barcode reader also has a Decoder to analyze the barcode’s image data from the sensor and to transfer it into the computer.
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