Please forward this error electricity and magnetism by b ghosh pdf to sharedip-1666228125. Wireless power techniques mainly fall into two categories, non-radiative and radiative.
These techniques can transport energy longer distances but must be aimed at the receiver. In wireless communication technologies only tiny amounts of power reach the receiver. For this reason, wireless power technologies are likely to be more limited by distance than wireless communication technologies. Electric tooth brush and razor battery charging, induction stovetops and industrial heaters.
Charging portable devices, power routing in large-scale integrated circuits, Smartcards. Charging electric vehicles, buses, biomedical implants. Powering drone aircraft, powering space elevator climbers. However time-varying fields can carry power. These fields can exert oscillating forces on the electrons in a receiving “antenna”, causing them to move back and forth. These represent alternating current which can be used to power a load. The boundary between the regions is somewhat vaguely defined.
If there is no receiving device or absorbing material within their limited range to “couple” to, no power leaves the transmitter. The range of these fields is short, and depends on the size and shape of the “antenna” devices, which are usually coils of wire. Therefore, these techniques cannot be used for long range power transmission. This is the range over which ordinary nonresonant capacitive or inductive coupling can transfer practical amounts of power. This is the range over which resonant capacitive or inductive coupling can transfer practical amounts of power. The portion of energy which does not strike the receiving antenna is dissipated and lost to the system. Therefore the near-field devices above, which use lower frequencies, radiate almost none of their energy as electromagnetic radiation.
Therefore, these can be used for short range, inefficient power transmission but not for long range transmission. Unlike in a radiative system where the maximum radiation occurs when the dipole antennas are oriented transverse to the direction of propagation, with dipole fields the maximum coupling occurs when the dipoles are oriented longitudinally. Modern inductive power transfer, an electric toothbrush charger. A coil in the stand produces a magnetic field, inducing an alternating current in a coil in the toothbrush, which is rectified to charge the batteries. A light bulb powered wirelessly by induction, in 1910.
Inductive coupling is the oldest and most widely used wireless power technology, and virtually the only one so far which is used in commercial products. Wide, flat coil shapes are usually used, to increase coupling. Ordinary inductive coupling can only achieve high efficiency when the coils are very close together, usually adjacent. This can achieve high efficiencies at greater distances than nonresonant inductive coupling. Customers can set their phones and computers on them to recharge. Another advantage is that resonant circuits interact with each other so much more strongly than they do with nonresonant objects that power losses due to absorption in stray nearby objects are negligible.
The case of using such a shifted peak is called “Single resonant”. The “Single resonant” systems have also been used, in which only the secondary is a tuned circuit. Resonant technology is currently being widely incorporated in modern inductive wireless power systems. One of the possibilities envisioned for this technology is area wireless power coverage.