Conduction and Induction - Mr. Hoover's Science Classes

Conduction and Induction - Mr. Hoover's Science Classes

CONDUCTION AND INDUCTION SNC1P Charged Objects An electroscope is an instrument that can be used to detect static charge. The study of static electric charges is called electrostatics. The electroscope was first invented in 1748 by a French

clergyman and physicist named Jean Nollet. A metal-leaf electroscope has two very thin metal pieces, called leaves, suspended from a metal rod. The metal rod is attached to a top plate or metal knob. When a charge is transferred to the plate or

knob, the charges spread out over the whole structure, including the leaves. The greater the charge, the greater the separation between the leaves. Detecting Static Charge When a negatively charged rod is brought near a neutral electroscope, the electrons in the

electroscope are repelled by the rod. The electrons move down into the leaves of the electroscope. The leaves are now both negatively charged, so they repel each other and move apart. The movement of the charges is called Charge Separation Detecting Static Charge When the negatively charged rod is

taken away, the negative charges in the electroscope are no longer repelled, so they move throughout the leaves, stem, and knob. The leaves drop down, and the electroscope is neutral again. Charging By Contact

Electrons can be transferred through contact and conduction. You can charge a neutral object by contact when you touch it with a charged object. Charging by contact occurs when electrons transfer from the charged object to the neutral object that it touches. Charging By Contact

The neutral object gains the same type of charge as the object that touched it because the electrons move from one object to the other Induction The movement of electrons within a substance caused by a nearby charged object, without direct contact between

the substance and the object. Example: Charging by Induction When charging an object by induction, a charged object is used to induce a charge in a neutral object and then ground the charged object so it retains the charge. This newly charged object has the opposite

charge to the charge on the charging object. Charging by Induction Grounding is the process of connecting a charged object to Earths surface. When you connect a charged object to the ground, you provide a path for charges to travel to or from the ground.

Electrical Discharge Once an object is charged, the charges are trapped on it until they are given a path to escape. When electric charges are transferred very quickly, the process is called an electrical discharge. This can be caused by induction. The discharge happens before contact actually occurs.

Example: Sparks or shocks Lightning Lightning is an example of a very large electrical discharge caused by induction. In a thunderstorm, a charged area, usually negative, builds at the base of the cloud. The negative charge at the base of the cloud creates a temporary positive area on the ground through the induction

process. Lightning When enough charge has built up, a path of charged particles forms. The cloud then discharges its excess electrons along the temporary path to the ground, creating a huge spark - lightning. This discharge creates a rapid expansion

of the air around it, causing the sound of thunder Air is normally an insulator. If it wasnt lighting would form every time that clouds formed. For lighting to occur, charges in the clouds must build up to the point where the air cannot keep the charges

separated from the ground. At this point, the air stops being an insulator and becomes a fair conductor, resulting in a lightning strike. Earth is a donator or receiver of charge and is so large that overall it is not affected by the electron transfer of huge lightning strikes. As a result, the ground is always considered

neutral Electrostatic Generators Scientists use several devices in the laboratory to study how static charges create lightning and other phenomena, such as the static that affects clothes coming out of the dryer. Electrostatic Generators

Early electrostatic generators were called friction machines because they used direct contact between different surfaces to create charged areas. A glass sphere or cylinder was rubbed mechanically by a pad to charge it up. Electrostatic Generators

More recent machines, such as the Van de Graaff generator, create charge through friction between the roller and belt and then transfer the charge to a large metal sphere A Wimshurst machine creates charges on two slowly rotating disks with metal strips placed around the disks. The charge is built up using induction

between the front and back plates as the disks turn in opposite directions. The excess charge is collected by metal combs with points near the turning disks Questions- hand in

1. What does an electroscope detect? 2. In the contact method of charging, what charge does a neutral substance gain compared to the object that touched it? 3. In induction, what charge does a neutral substance gain compared to the object brought near it? 4. What is the difference between charging by contact and charging by induction in terms of electron transfer? 5. What is grounding?

Recently Viewed Presentations

  • Terrestrial and Aquatic Biomes

    Terrestrial and Aquatic Biomes

    Biome- large grouping of ecosystems that have the same climate and similar groups of communities. ... Major Land Biomes Chaparral. Found in areas with less rainfall than temperate forests. ... On your Georgia map find and label ALL of the...
  • "99 red balloons"by Nena (or "99 Luftballoons")

    "99 red balloons"by Nena (or "99 Luftballoons")

    "99 red balloons"(or "99 Luftballoons") "99 Red Balloons" is a song written in 1983 by German techno-pop band Nena. It was a top hit on the charts in the early 80s…
  • Decanting - A New Look at an Old Friend

    Decanting - A New Look at an Old Friend

    Common Law . Cases: Phipps, 142 Fla. 782 (1940) "The general rule gleaned from the foregoing and other cases of similar import is that the power vested in a trustee to create an estate in fee includes the power to...


    Integrated Forest Pest Management "The combination of all suitable techniques to reduce or manipulate pest populations so that they remain below economically important levels" Questions to for Principals of Forest Insect Management: 1) What are the basic differences in management...
  • Chapter ...

    Chapter ...

    Instruction Execution. PC instruction memory, fetch instruction. Register numbers register file, read registers. Depending on instruction class. Use ALU to calculate. Arithmetic result. Memory address for load/store. Branch target address. Access data memory for load/store. PC target address or PC...


    Then pro-collagen chains are translocated to Golgi- apparatus. In the golgi they are packaged in secretory vesicles. These vesicles fuse with the membrane and release the . pro-collagen molecule into the extracellular space. 5. Extracellular cleavage of Procollagen molecules:
  • CPAN 410 & GAME 410 Project Management

    CPAN 410 & GAME 410 Project Management

    CPAN 410 & GAME 410 Project Management Nicoleta Zouri Email: [email protected] 1. Assignments 2. Case studies/Quizzes 3. Midterm Exam 4. Final Project - teams Note: must obtain 60 or more in the midterm exam and final project for the assignments...
  • ACLS CH05 - Chester County Intermediate Unit

    ACLS CH05 - Chester County Intermediate Unit

    First artificial heart, the Jarvik-7, was connected to an external power source and pump. 2001 - AbioCor self-contained artificial heart Designed to extend life for people with end-stage heart failure who had no other clinical options Helps provides a good...