摘要 |
<p>An information providing apparatus such as a question and answer game has: a substrate (3) carrying visually identifiable ink dots comprising first and second inks of the same colour with one of said first and second inks comprising an ink that emits radiation of a first wavelength in response to receipt of radiation of a second wavelength different from the first wavelength; a detector (4) for detecting radiation of the first wavelength and for providing a detection signal indicating whether or not radiation of the first wavelength has been detected; and user advising means (9) for advising a user when the detector is receiving radiation of the first wavelength.</p> |