Electricity

Electric Currents

flow of electric charges in space in a given direction. It exists when there is a net flow of electric charge in a specific direction in space

Electric Circuits

Set of electrical components connected in a way to provide one or more complete paths for the movement of charges

Closed Circuits

Path where the electricity that is produced when the light bulb is connected to the battery

Open Circuits

There is no flow of charges therefore there is no current

Ohms Law equation

Triangle (v/I*R)

Direct Current

magnitudes remain constant over time, always in the same direction. Direct current is provided by batteries, as in the case of flashlights and radios.

Alternating Current:

The current varies alternately in direction and magnitude. They are produced by electrical forces that alternately change direction and intensity, that cause a back-and-forth movement or oscillations of the charges.

Remember that in a parallel circuit:

The current in the branches of the circuits adds up. The voltage is the same across each branch. To calculate total resistance use reciprocals.

Remember that in a series circuit:

• The current in every part of the circuit is the same.

• The voltage supplied by the battery is the voltage of the circuit, and the voltage drops across each resistor, adds up to the total voltage. -To calculate total resistance, add the value of the resistances.

Electrons

negative

Protons

Positive

Neutrons

Neutral

Properties of an Electric Charge

Two kinds of charges occur in nature.

Like charges repel one another.

Unlike charges attract one another.

Charged is conserved.

Charge is quantized.

Charged by Conduction

Charge for contact, Charge a neutral body by contact with another charged body.

Charge by Induction

Happen without contact. Charge a neutral object by bringing it closer to a charged object, causing a separation of charges.

Conductors

Any materials that allows electric current to pass through it. It is characterized by having many free electrons.

Examples of Conductors

silver, gold, copper, steel, sea water

Insulators

Any material does not allow electric current to pass through it. Has greater difficulty giving up or accepting electrons.

Examples of insulators:

glass, plastic, wool, diamond, rubber

Semiconductors

Materials that are less likely to give up electrons when an electric current passes through them, and his major characteristic is to let it go through only one direction and prevent it from going in the opposite direction.

Examples of Semiconductors:

Silicon, and gallium

Coulomb’s Law:

states that the force between two points charges is directly proportional to the product of their charges and inversely proportional to the square of their distance apart. The closer two charges are, the stronger the force between them.

Coulombs constant

9.0 * 10^9 Nm^z /C^2

Kirchhoff's Current Law, (KCL)

In other words the algebraic sum of ALL the currents entering and leaving a node must be equal to zero, I(exiting) + I(entering) = 0.  (conservation of charge)

The Voltage Law, (KVL)

 In other words the algebraic sum of all voltages within the loop must be equal to zero.  (conservarion of Energy)

voltmeter

is used to measure the electrical potential difference between two points in a circuit. Calculates the voltage in volts

Why is the voltmete is used for?

The voltmeter is used to measure potential difference.

Why the voltmeter is connected in parallel always?

Since objects in parallel experience the same potential difference. Voltage remain constant, you can calculate it. The voltage in the circuit remains unchanged.

ammeter

device connected to a circuit to measure the current flowing through the circuit.

What happened it is connected in parallel?

If the ammeter is connected in parallel, then due to its low resistance, it will act like a short circuit.