ElectroDroid is a simple and powerful collection of electronics tools and references. It is available for free, but you can buy the ad-free version too.
Build any circuit, tap play button, and watch dynamic voltage, current, and charge animations. This gives you insight into circuit operation like no equation does. While simulation is running, adjust circuit parameters with analog knob, and the circuit responds to your actions in real time. You can even generate an arbitrary input signal with your finger!
Electrical Engineering Pack consists of 39 Electrical Calculators and 16 Electrical Converters. A complete guide for Electrical Engineers, Technicians and Students.
This is a very useful app for electrical and electronic engineering students. It performs a variety of activities and is available in an array of languages.