* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download electrical current - Fulton County Schools
Survey
Document related concepts
Valve RF amplifier wikipedia , lookup
Thermal runaway wikipedia , lookup
Switched-mode power supply wikipedia , lookup
Operational amplifier wikipedia , lookup
Index of electronics articles wikipedia , lookup
Power MOSFET wikipedia , lookup
Lumped element model wikipedia , lookup
Negative resistance wikipedia , lookup
Nanogenerator wikipedia , lookup
Opto-isolator wikipedia , lookup
Resistive opto-isolator wikipedia , lookup
Surge protector wikipedia , lookup
RLC circuit wikipedia , lookup
Current source wikipedia , lookup
Nanofluidic circuitry wikipedia , lookup
Electric charge wikipedia , lookup
Rectiverter wikipedia , lookup
Transcript
Electricity & Magnetism Where science and magic meet Electricity • is the flow of electrons, described as an electrical current. • Electrons are negative, so the electrons move from a negative pole towards a positive pole. • Electricity can be described as the forces between charges. Circuits • A circuit describes the path that electrons flow through. • If there is a break in the circuit, the electric current will not flow. Circuits • An incomplete or broken circuit is said to be an “open circuit”. • A complete circuit is called a “closed circuit”. • Switches are devices designed to make a circuit open or close. Oops! • A short circuit occurs when the electrical current finds a “short cut” across the circuit. • When this happens, the electricity jumps across the path of least resistance, and the designated work, or load, is not accomplished. What about it? • While the study of electricity is relatively new (less than 200 years), a great deal of investigation has been done recently • Due to innovations in the modern electrical world (1920 –) Charges • A charge is a point source of electrical force. • There are only two charges; Positive and Negative. Rule of Charge • The Rule of Charges is stated: “Opposites Attract, Likes Repel” Charges in the world • Most common objects are neutral (having the same number of + and – charges) • An object which has more of one charge than another is said to be charged. Shocking! • The buildup of charges on an object is static electricity. • When the static charges do move, it is called an electrical discharge (the charges move along the path of least resistance). Shazam! • Lightning is a form of electrical discharge. • The static charges are formed when the particles inside the storm cloud rub against each other, separating charges. Lightning Lightning How to charge • Induction – Bringing a charged object near an uncharged object causes the like charges to run away and attracts the opposite charges – Give the like charges an “out”, leaving the opposites How to charge • Conduction – Touching a charged object to an uncharged object causes the charges on the charged object to spread through the two objects Voltage • Amount of PE that each unit of electrical charge has • V= I x R • Voltage (volts)=Current (amperes) x Resistance (ohms) Power • Power is measured in Watts (W) • Power = Voltage x Current • W=Volts x Amps Ohm’s Law • Describes the mathematical relationship present in most circuits Current • Quantity that refers to the rate of flow of electric charges • I = V/R • Current = Voltage/Resistance • Amps = Volts/ohms Resistance • Conductor – allows the flow of electrons • Insulator – DOES NOT allow the flow of electrons Resistance • The measure of an object’s ability to conduct electrical current • R = V/I • Resistance = Voltage/Current • Ohms = volts/amps What is the difference between placing a 1.5 V battery or a 9 V battery in a circuit? Increase the amt. of current flow ? • Greater voltage battery or more smaller batteries • Shorter, thicker wire • More conductive metal • Light bulb with lower resistance Decrease Resistance? • Shorter length wire • More conductive metal • Thicker wires Resistance & Current • High resistance = low current • Low Resistance = high current A d d V o l t a g e Open or closed circuit ? One bulb • Single Resistance • Full current Two bulbs • Double the resistance • ½ the current Three bulbs • 3 times the resistance • 1/3 the current S e r i e s Series Circuit Series or Parallel ? Series Circuit • Current only follows one path • Amount of energy used by a circuit must equal the energy supplied by the battery • Ex: cheap X-mas lights Parallel Circuit • Current has two or more possible paths • Each path is called a branch • Same amt. of current must flow out again • Ex: your house (ask me to explain!) P a r a l l e l Parallel Parallel AC or DC ? • AC or alternating current – direction of the current goes back and forth • In the US, most electrical systems have a current that reverses 60 times per second • Ex: your house AC or DC ? • DC or direct current – current that flows in one direction • Ex: a battery Ground wire • For safety • Connected to the ground near your house • Ex: if your fridge has a short circuit, then the electricity will flow into the ground instead of through YOU! Nikola Tesla • Physicist, Mechanical Engineer • Many investigations w/ AC • AC is easier to produce and cheaper to use