**Physical Quantities and**

**Measurements:**

**Charge (Q)**measured in c

*oulombs (C)***Current (I)**measured in

*amperes (A)***Time (t)**measured in

*seconds***Electrical Potential Difference (Voltage)**measured in v

*olts (V)***Energy (E)**measured in

*joule (J)*

__Facts Learned:__• Current is the total amount of charge in Coulombs that goes through a point in a conductor, divided by the time it takes. Current is symbolized by I. The formula is:

I (Current in Amperes) = Q (charge in Coulombs) divided by t (time in seconds) or

**I = Q / t**

• The base unit for current is C/s which is named Ampere. It is represented by (A). One ampere = one Coulomb of charge moving through a point in the conductor / second.

• Conventional current flow vs. electron flow:

- Conventional current flow is from positive to negative.

- Electrons are negative and flow from negative to positive.

• Voltage vs. Current

- Voltage is the electrical potential difference between two points.

- Voltage would move from a point of higher potential to a point of lower if given the chance (until the levels equalize).

- Current is the rate of flow of charge.

• In coloured writing convention used to keep track of electron current flow, black represents the negative terminal and red represents the positive terminal.

• In a direct current, the current flows in one direction. It flows from the power supply, through the conductor, to a load, and back to the power supply.

• In an alternating current the electrons reverse the direction of their flow periodically, with the help of electric and magnetic forces.

• Work is done by the power supply to increase the electrical potential energy of each coulomb of charge from a low to a high value. As the charge flows through a load, its energy decreases.

The electric potential energy (voltage) for each Coulomb of charge in a circuit is called the electric potential difference.

• The energy (needed to do work) = electric potential difference * charge or

**E = Q* V**

• 1 Volt is the electric potential difference between two points (if 1 joule of work is required to move 1 coulomb of charge between 2 points.

__Resources:__http://www.differencebetween.net/technology/difference-between-current-and-voltage/

http://www.wordiq.com/definition/Potential_difference

http://www.educationalelectronicsusa.com/p/current_electricity-I.htm

**Video:**

You can aslo check the Video on Electric Circuits

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