How about locating a scar in your hand. One can easily detect it by simply by looking at it with the help of one’s own eyes if that person doesnt have any vision related problems. How about locating a scar on one’s face. One needs to look for a mirror or a camera. How about locating a tumor in one’s body. Now one is in need of a special device to look into the body as one just cannot cut open or operate body every time. This special device is MRI (Magnetic Resonance Imaging). As its name suggests it uses magnetic field for imaging. Our body is made up of millions of atoms. These are in constant random motion. Especially there are a large number of water molecules which contain hydrogen that possess high magnetic moment, meaning it can align itself in presence of magnetic field. So, using magnetic field one can align the protons in one direction. When additional energy in the form of a radio wave is given, the magnetic vector gets deflected causing the hydrogen nuclei to resonate. Different slices of the body resonates with different frequencies. When the radio wave is turned off, the magnetic vector returns to the resting state and causes a signal to be emitted. These signals are used to create the MR images. In a nutshell, the mechanism of MRIs are more like a carbon copy paper where the force applied by the pen is the radiowave.