Yenka is described as 'new generation of educational modelling tools from Crocodile Clips' and is an app in the Education & Reference category. There are five alternatives to Yenka for a variety of platforms, including Windows, Linux, Online / Web-based, Mac and Android. The best alternative is Circuit Simulator, which is both free and Open Source. Other great apps like Yenka are Everycircuit (Freemium), PSIM (Paid), BrainBox (Free, Open Source) and Multisim (Paid).
Physical things are great. Hardware companies like Apple, Arduino, etc are disrupting our lives in a big way. At BrainBox we love hardware hackers and are in absolute awe of their awesome design and applications they build.