hat mobile devices don't draw current from backlights in daylight. Another way that manufacturers design handsets to improve power management is by including automatic sensing circuitry that shuts down memory, processors, and peripherals when a handset is not transmitting. For example, if the user is not in a Wi-Fi zone, the Wi-Fi circuitry is disabled SO that it does not draw power when it can't even be used. Most smartphones and tablet computers include this form of power man- agement. Other manufacturers are developing new screen technologies that consume less power. In addition to research on display screens, batteries, and power management, com- panies such as Qualcomm are developing more convenient ways to charge phones. It is in the process of developing a magnetic tray on which people can place multiple wireless devices for automatic charging without plugging the device or the magnetic tray into an electrical outlet. So, instead of tossing a phone in a kitchen drawer or on dresser in the evening before going to bed, users would be able to simply place it on a tray and have a fully charged device waiting for them in the morning. Charging mobile devices gradually wears down the battery and shortens its life. Over time, batteries hold charges for shorter amounts of time. This is because every charge deposits chemicals on the device's contacts. These chemicals corrode the contacts creating resistance to the charge. A lithium-ion (Li-ion) battery experiences Handheld Devices and Tablet Computers corrosion in a different manner, but it, too, becomes resistant to charges. Thus, less voltage reaches the circuitry that carries the current to the battery. Voltage refers to the "pressure" of the electricity flowing through the handset's circuits. Low "pressure" or voltage means that less electricity is reaching the battery. Tablet Computers and the Increasing Amount of Traffic They Generate Tablet computers are another source of increased data traffic on mobile and Wi-Fi net- works. Despite its relatively high price