Abstract: A cooktop appliance includes a cooking surface configured for receipt of a cooking utensil and an induction heating element operable to inductively heat a load with a magnetic field. The induction heating element includes a coil. The cooktop appliance also includes a sensor. The sensor is operable to detect a location and an efficiency of the cooking utensil. The sensor may be positioned between the coil of the induction heating element and the cooking surface and/or may include a plurality of semi-circular loops spaced apart around a circumference of the coil.

Abstract: A writing system includes a pen with a two-dimensional optical sensor and a three dimensional acceleration sensor positioned to indicate movement of the pen. A calibrator is coupled to receive path coordinate signals from the two-dimensional optical sensor and the three dimensional acceleration sensor. The calibrator and the two-dimensional optical sensor and the three dimensional acceleration sensor are configured to operate in one of two modes, a contactable mode of operation wherein both the two-dimensional optical sensor and the three dimensional acceleration sensor supply path coordinate signals to the coordinator and a contactless mode of operation wherein only the three dimensional acceleration sensor supplies path coordinate signals to the coordinator.