A free program for Android, by Peter Ho.

Electronics Toolbox is an electronic calculator app. This app includes basic tools for electronics such as:

Basic electronics tools such as resistors, capacitors, transistors, diodes, and more.

The app has a list of electronics resources that you can use, such as:

A resistor is an electrical component that allows an electrical current to pass through it, according to the direction of the current flow. Resistor types vary in their properties, such as resistance, temperature, and physical dimension.

Capacitor is a component that allows an electrical charge to accumulate on its surface.

Transistor is a semiconductor device that switches current on and off, in response to a voltage applied to its terminals.

Diodes are electrical components that allow an electric current to pass through them, but not in the same direction as the current flow. Diodes have two terminals that receive the current, and two terminals that allow the current to flow in the desired direction.

The Basic Electronics Tools app also includes a list of tools for electronics, such as:

A multimeter or a magnetic meter is a device that measures the magnitude of magnetic fields.