Static Electricity Phenomenon and Forces" (67 characters)
Explore the intriguing world of static electricity, from clothes sticking together to crackling noises and electric shocks. Learn about the science behind static electricity, its causes, and how objects acquire charge through various methods. Delve into the forces and experiments related to static electricity, including Coulomb's experiments and electric field interactions. Unravel the mysteries of static electricity and its impact on everyday experiences. (471 characters)
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Presentation Transcript
Electricity Do your clothes stick together when you take them out of the dryer? Have your clothes ever made crackling noises when you took them off? Have you ever gotten an electric shock from another person? Have you ever seen sparks in your blanket at night?
A force must be pushing the hair apart
Why ??? Static Electricity Static electricity occurs when there is a build up of electric charge on the surface of a material. It is called static electricity because the charges don t move (much).
Static Electricity Ben Franklin (and others) Two types of electric charge Plus and Minus names Like repel unlike attract Yes the kite is real
Static Electricity Coulomb Experiment F=KQ1Q2 r2
Static Electricity Force (F) is in newtons (N) Charge (Q) is in coulombs (C) Distance (R) is in meters (m) Coulomb Constant (k) 9 X 109 Nm2/C2 F=KQ1Q2 r2
Static Electricity You and your lab partner each have a net charge of one coulomb of excess positive charge and are about one meter apart. What is the force between you? (You weigh about 500N) F=KQ1Q2 r2
Static Electricity How does one charge exert a force on a second charge when they do not touch? Electric Field
Small charged grass seeds in oil between two charges.
Static Electricity How do objects acquire charge? Charging by friction Induced charge separation Temporary Charging by contact Charging by induction
Charging by Friction When a balloon rubs a piece of wool... electrons are pulled from the wool to the balloon. + + + Rubber has a higher electron affinity than wool + + wool The balloon becomes negatively charged and the wool positively charged
Electroscope No Charge- leaves hang straight down
Contact Rod with negative charge
Contact Rod with negative charge
Contact Rod with negative charge Transfers electrons
Contact Rod with negative charge Transfers electrons Extra negative charge
Contact Rod with negative charge Transfers electrons Extra negative charge Move leaves apart.
Contact Remove rod leaves stay apart.
Induced Charge Separation After being rubbed, a plastic ruler can attract small bits of paper. WHY ???
Induced Charge Separation when a charged rod is close to paper scraps... Electrons are repelled. - - - - - - - The attraction between the rod and + charge is greater than the repulsion between the rod and - charge. attraction + + + + paper + + + + repulsion
Induced Charge Separation Rod with negative charge
Induced Charge Separation Rod with negative charge Pushes electrons in electroscope down
Induced Charge Separation Rod with negative charge Pushes electrons in electroscope down Extra negative charge
Induced Charge Separation Rod with negative charge Pushes electrons in electroscope down Extra negative charge Leaves move apart
Induced Charge Separation Remove rod everything returns
Excerpt From an Electric Novel Carol put the gas pump nozzle on automatic and re-entered her car to write a check. Just then her daughter, wearing a wool sweater and nylon jacket and who's hair was standing out, reached out the window for the nozzle. Flames suddenly ignited her clothing.
What Happened? When you touch a positively charged metal ball electrons flow from the earth to the metal ball, neutralizing the charges. + + + This is called + + Grounding
Charging by Induction Bring a negatively charged rod near an object to produce induced charge separation - - - - - induced charges - - +++++ - - - -- metal can
Charging By Induction Bring a charged rod near an object to produce induced charge separation
Charging By Induction Ground the object. Allowing electrons to flow
Charging By Induction Remove the ground, then remove the rod.
Current Electricity Current electricity is the rate of flow of charge. Current (I) Ampere (A) or (C/s) Electrons in metals Protons, Electrons or ions in liquids and gasses AC / DC
Current Electricity Conductors Insulators Resistance (R): A material s opposition to the flow of charges Ohms ( ) Thickness, length, temperature (for metal wires)
Current Electricity Electric Potential Difference (V): The difference in the amount of energy that a charge has between two spots in an electric field J / C or Volt (V) Gravity potential energy battery
Electricity Ohm: Was able to relate current, resistance and potential difference for a circuit. V = IR Read 20.2
Electric Circuits Electric Circuit: a complete (closed) path that allows electricity to flow Circuit diagram: Uses symbols to represent the parts of an electric circuit
Electricity Series Circuit One path I is constant = = = I I I ... T 1 2 = + + V V V ... V adds R adds T 1 2 = + + R R R ... T 1 2
Electricity Parallel Circuit More than One path (branches) = = = V V V ... V is constant T 1 2 = + + I I I ... I adds T 1 2 1 R 1 R 1 R R goes down = + + ... T 1 2
Electricity Power: how quickly the energy is transferred P = energy / time J/s watts W P = VI
Electricity Safety Fuse Circuit breaker Gfi Read 20.3
