1. ElectroDroid
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.
2. EveryCircuit
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!
3. Lessons In Electric Circuits
This is a good one for students. It covers 5 volumes with the following topics,
Volume. 1 -- DC
Volume. 2 -- AC
Volume. 3 -- Semiconductors
Volume. 4 -- Digital
Volume. 5 -- Reference
Volume. 6 – Experiments
4. DroidTesla
DroidTesla is a simple and powerful SPICE engine. SPICE is an acronym for Simulation Program with Integrated Circuit Emphasis
5. Electronics Toolkit
Provides a useful interface for calculating unknown quantities in the fields of electronics and electrical engineering.
6. Electrical Pro
This app is a compilation of five sub apps that use the 2008/2011/2014 National Electric Code (NEC).
7. Electrical Engineering Pack
Electrical Engineering Pack consists of 39 Electrical Calculators and 16 Electrical Converters. A complete guide for Electrical Engineers, Technicians and Students.
8. Electrical Wiring
This is another calculator that lets you find various results that are useful in electrical and eletronic engineering.
9. Electrical Calculations
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.
10. Electrical LV Calculator
Quick Reference Implementation for the main calculations requested by the Low Voltage Electrotechnical Regulations.