Electric Current – the rate of charge flow past a given point in an electric circuit, measured in Coulombs/second which is named Amperes. In most DC electric circuits, it can be assumed that the resistance to current flow is a constant so that the current in the circuit is related to voltage and resistance by Ohm’s law.

- alternating current (AC) – an electrical current whose magnitude and direction vary cyclically. The usual waveform of an AC power circuit is a sine wave, as this results in the most efficient transmission of energy. This is the form in which electricity is delivered to businesses and residences.

- direct current – an electrical current whose direction remains constant.

- electricity
- electrical circuit – a path along which electricity can travel.
- resistor
- conductor
- voltage

**That’s engineering**

- voltage
- resistance – the repulsion of a current within a circuit. It explains the relationship between voltage (amount of electrical pressure) and the current (flow of electricity).
- Ohm’s Law – Resistance, discovered by Georg Simon Ohm in 1827, is the ratio between voltage and current. Ohm’s law said that the voltage between any two points in a conductor changes directly as the current between the two points, given the temperature remains the same.

**Engineering ideas**

- electricity, electrical current, amperes, circuits, resistance, current, flow, voltage, resistance, conductor, sine wave, direction, modulation, amplitude

**Do It**

Challenges for you to work on…

- Ohm’s Law – interactive simulation
- Glow Sticks (video 2:16) – When all parts of the circuit are connected, electricity flows from the battery to the lights and back to the battery, making your glow stick glow!
- Squishy Circuits (video 7:04) – making conductor dough and insulator dough. With a special recipe of food-safe, kitchen-made, pliable dough developed at the University of St. Thomas, use your hands to mold your very own simple circuits right before your eyes. * Squishy Circuits – The home of all things related to Squishy Circuits * Squishy Circuits Store – Kits of LEDs and other parts that work well with squishy circuits