The book is ideally suitable for the Students of Diploma, Vocational Trainee's and I.T.I's offering similar courses. The present book aims at imparting purely experimental knowledge besides promoting easy grasp and simple way of presentation. This book will help the taughts adequately about the appliances and devices that come to their way in their daily lives. Their aptitude to learn things with a scientific bent of mind and their urge to learn by practical experimentation through simple experimental devices have been developed in the right proportion.