what is the use of near field communication
Near-field communication NFC devices are used in contactless payment systems, similar to those used in credit cards and electronic ticket smartcards and allow mobile payment to replace/supplement these systems. This is sometimes referred to as NFC/CTLS (Contactless) or CTLS NFC. NFC is used for social networking, for sharing contacts, photos, videos or files.[2] NFC-enabled devices can act as electronic identity documents and keycards.[3] NFC offers a low-speed connection with simple setup that can be used to bootstrap more capable wireless connections.[3]
R-C coupled R-C coupled coupling is the most widely used method of coupling in multistage amplifiers. In this case the Resistance R is the resistor connected at the collector terminal and the capacitor C is connected in between the amplifiers. It is also called a blocking capacitor, since it will block DC voltage. The main disadvantage of this coupling method is that it causes some loss for the low frequency signals. However, for amplifying signals of frequencies greater than 10Â Hz, this coupling is the best and least expensive method. It is usually applied in small signal amplifiers, such as in record players, tape recorders, radio receivers, etc.