Have you ever felt annoyed when left talking to yourself after your mobile phone battery runs out in the middle of a call? If yes, then here comes some good news. Scientists are now perfecting a way to recharge electrical equipment while on the move.     Researchers from theprefix = st1 /Netherlands,FranceandPortugalannounced last week that they have developed very thin solar panels that can be put on clothes. They can also be added to furniture and rooftops. They change light from the sun into electricity.     In about three years, you'll be able to wear a jacket that will recharge your phone as you walk. For camping fans, the development could lead to a tent which charges batteries all day so you can have light or music at night.     The basic technology of wearable solar panels is the same as that used for traditional solar panels. Pairs of sheets of semi-conducting silicon   are linked together to form the panel. But scientists made them much thinner by using different silicon. At one micrometre, they are of the same thickness as photographic film.     "This technology will make it easier for people to use clean energy sources," said a physicist in theNetherlandswho led the team of scientists. But the thin panels are not as efficient as the thicker ones. While some solar panels now operate at an efficiency of about 20 per cent, the new flexible   panels are only 7 per cent efficient. But the thinner panel is cheaper. An A4 sized panel put onto the back of a jacket cost less than US$13. It could charge a cellphone during a summer walk in the countryside. As long as you stay within range of the transmitting masts   that relay a call to the networks, phones will never again run out of power. Which of the following is TRUE about the electrical equipment?
It can only be used while camping. You can listen to some music on it. It will be put into use in a few years. It can only be used as you walk.