Checkpoint+Electricity+and+Electrostatics

=// ELECTRICITY //=

To distinguish between conductors and insulators
Aim: To find out which materials conduct electricity?
 * Material || Does a bulb light? || Conductor of Insulator? ||
 * scissors ||  ||   ||

Conclusion The good conductors were ... a__ ll metals __, g __ old, __ __c arbon __, .... The insulators were ... __w ood __, __p lastic __, __c lothing __....

**Insulator or conductor: Is air an conductor?**
Insulator: A material that does not easily allow __ electricity __ to pass through it. Examples) Air, Cloth and Rubber Conductor: A material which contains movable __ electric charges __. Examples)

Homework
1. Do workbook 3 page 63. 2. Copy the diagrams below in your jotter book.

To understand the value of circuit diagrams




To understand the effects of further components
// Workbook3 page 63. // Insulators (electrical nonconductors) contain no charges that move when subject to a voltage. || Air, cloth and rubber are good electrical insulators; Feathers and wool make good thermal insulators. Non-metals;plastic rubber, glass, wood || Circuit diagram ||
 * **Insulator** || A material or an object that does not easily allow heat, electricity, light, or sound to pass through it.
 * **Conductor** || A material or an object that allows heat, electricity, light, or sound to pass through. Electrical conductors contain electric charges (usually electrons) that are relatively free to move through the material || Most metals such as copper, iron, aluminum, body ||  ||
 * Resistor || A device having a designed resistance to the passage of an electric current. ||  ||   ||
 * Electrical switch || A device for making and breaking the connection in an electric circuit ||  ||   ||
 * Component || Something in a circuit like a bulb, switch or a motor. ||  ||   ||
 * Ammeter || A device measuring ||  ||   ||
 * Voltmeter || A device measuring ||  ||   ||
 * Variable resistor || A resistor that can control various range of resistances. ||  ||   ||
 * Capacitor || A charge storing device. ||  ||   ||
 * Fuse || A safety device (consisting of a strip of wire) that melts and breaks an electric circuit if the current exceeds a safe level. ||  ||   ||

Resistance is anything that resists an electric current || The greater the resistance in a circuit, the lower the __ current __. It is measured in __ ohms __. ||
 * **Electricity** || Electric current/ Energy made available by the flow of electric charge through a conductor. ||  ||
 * //__**Current**__// || The rate of flow of electricity charges. || It is measured in __ amperes __. ||
 * __//**Resistance**//__ || The opposition to current in a circuit.
 * __//**Circuit**//__ || A complete __ path __ through which an electric current can flow ||  ||
 * Brainpop**: Electricity, Electric circuit, Current electricity, Batteries

Measure current using ammeters and voltage using voltmeters, including digital meters

 * Aim:** To investigate the voltage differences between series and parallel circuits.

Simple Circuit

1. Draw a circuit symbol that has 2 bulbs and 2 cells in series. 2. Draw a circuit symbol that has 2 bulbs and 2 cells in parallel.
 * Method:**

3. Set up the circuit 1. 4. Measure the voltage across the each bulb. 5. Set up the parallel circuit 2. 6. Measure the voltage across the each bulbs. 7. Measure the total voltage that you used across the cells 8. Repeat the step 1 to 6 with 3 bulbs.

Results: Homework for Grade 7 Amber on 6th December. 2013 Draw each diagram series and parallel circuit that includes 2 light bulbs and battery of 4 volts. Fill in the table below.


 * Investigating c __ urrent __ in a c __ ircuit __ || Volts in Series || Volts in Parallel ||
 * Total voltage that you have used ||  ||   ||
 * Bulb 1 ||  ||   ||
 * Bulb 2 ||  ||   ||
 * Bulb 3 ||  ||   ||
 * Bulb 4 ||  ||   ||

In a series circuit, there is only one __ path __ for electrons flow. The amount of current is __the same__ in the entire circuit. In a parallel circuit, there are more than one path for electrons flow. The s__ um __ of the current in each branch is equal to the total current in the circuit.
 * Conclusion**

Model and explain how common types of components, including cells (batteries), affect current.
Aim: To investigate the difference in amount of current in series and parallel circuits.

Conclusion In a **series circuit,** the current has only one __p ath way __ to take so each bulb receives in the same amount of __c urrent. __ The __e lectrical p otential e nerg __ y (V oltage ) is shared between the bulbs. The more bulbs there are, the dimmer the lights. In a **parallel circuit,** the current has more than one __p ath __ to take so each bulb receives in a fraction (one of the total number of paths) of amount of __c urrent. __The __e lectrical p otential e nerg __ y (V oltage ) is NOT shared between the bulbs. The brightness of all the bulbs are the same.

[|Series and Parallel Circuit] from animatedscience.co.uk [|Circuit Practice Test] from BBC Bitesize [|Difference between Series and Parallel circuit] from Slideshare

** Complete workbook 3 : page 63 - 66 by Wednesday 19th Dec. **
BBC KS3 Bitesize Electric current and voltage video activity BBC KS3 Bitesize [|Electric current and voltage]

Research on electricity
Take a note after reading your text page196 - 197.

Homework:
Choose one of the scientist that took an important role for us to use electricity and make a short presentation.(5minutes)You will present yourself as the scientist in front of your classmate.

[|**Benjamin Franklin**] was one of seventeen children. He quits school at age ten to become a printer. His life is the classic story of a self-made man achieving wealth and fame through determination and intelligence. His kite experiment demonstrated that lightning is electricity. He was the first to use the terms positive and negative charge.
 * //Other stories://**

Benjamin Franklin: At the age of forty-two, I retired from printing to explore my other interests. I devoted this time to inventing. During my life, I invented many things, including:

Swim fins, bifocals, a glass armonica, watertight bulkheads for ships, the lightning rod, an odometer, and the wood stove (called the Franklin stove).

In addition to inventing, I enjoyed experimenting. One thing that always fascinated me was electricity. so, one stormy night my son, William, and I were experimenting with lightning. You see, during my time, people thought that lightning was a mysterious force that was a punishment from God; however, I wanted to prove that lightning is a form of electricity.

I attached a pointed metal piece on the top of my kite and a metal key to the base of the string. Lightning struck the kite and traveled down the kite string to the key. When I touched the key with my knuckle, there was a spark! It's a good thing I didn't electrocute myself (although I was knocked unconscious twice before when experimenting with electricity, so don't try this at home!), but I did prove that lightning is electricity! Afterwards, I invented the lightning rod to protect buildings and ships from lightning damage. Although I received much recognition from my inventions, I did not profit from them. Instead, I chose to give my inventions to the world freely.

**[|Michael Faraday] (1791-1867)** an Englishman, made one of the most significant discoveries in the history of electricity: Electromagnetic induction. Failures never discouraged Faraday. He would say; "the failures are just as important as the successes." He felt failures also teach. from Electrical History book by Tom Henry.

lessandro Volta vs Luigi Galvani
One contemporary of [|Alessandro Volta] was [|Luigi Galvani], in fact, it was Volta's disagreement with Galvani's theory of galvanic responses (animal tissue contained a form of electricity) that led Volta to build the voltaic pile to prove that electricity did not come from the animal tissue but was generated by the contact of different metals, brass and iron, in a moist environment. Ironically, both scientists were right. from About.com

[|lick to read history of electricity1]
[|Click to read history of electricity2]

[|Click to read history of battery]

=// ELECTROSTATICS //=

**Electrostatic charges**
When an insulator or conductor has static electricity, it contains an imbalance of positive or negative charges.

Image from www.wpclipart.com
 * Structure of an atom**

**Induced charges**
Image from www.jeron.je Image from www.johnhearfield.com
 * Aim:** To investigate if an insulator attract or repel materials after being rubbed by fur or fleece.

Explain why the paper is attracted to a comb rubbed by animal fur. Explain why a balloon rubbed by fleece or hair is attracted to the wall.
 * Conclusion**

The comb attracts pieces of paper when charge builds up due to __s tatic __ electricity. The balloon attracts to the wall where __i nduced __ charge builds up. The balloon gained __e lectron s__ from being rubbed by hair then __n egatively __ charged. It attracted to the __p ositive __ charges on the wall.

Define the word 'Statics' Not __ moving __. No __ motion __. •Some insulating materials become electrically charged when they are rubbed together by gaining or losing __e lectron s.__

ex) Paint Sprayer – charged paint droplets repel each other creating a thin, evenly spread mist. Object – the object (i.e. car door, bicycle, e.g.) has the opposite charge so that the paint is attracted to it, this produces an even layer and stops paint being wasted

A force that __r esists __ the relative motion of two bodies or substances in __c ontact .__
 * Challenge:** What is 'Friction'?

How can you make it a fair test?

Images from www.tech2play.blogspot.com
 * **Induced charges** || **Like charges __ repel __, opposite charges __ attract __.** ||
 * [[image:Induced charges.JPG width="384" height="114"]] || [[image:sciencelanguagegallery/like repel unlike attract.JPG width="243" height="122"]] ||

Read your textbook page 200 and 201.
 * Homework:**

Van de Graaff Generators
from howstuffworks.com


 * When the motor is turned on, the lower roller (charger) begins turning the belt. Since the belt is made of rubber and the lower roller is covered in silicon tape, the lower roller begins to build a negative charge and the belt builds a positive charge.** **Silicon is more negative than rubber; therefore, the lower roller is capturing electrons from the belt as it passes over the roller.**


 * As long as there is air between the lower roller and brush assembly, the Van de Graaff generator will continue to charge the belt.** **The belt** **is positively charged and rolling toward the upper roller and upper brush assembly.** **The upper brush assembly is connected to the inside of the sphere and hangs near the upper roller and belt location. The electrons in the brush move to the tips of the wires because they are attracted to the positively charged belt.** **At the same time, the free electrons in the air move to the belt. When a charged object touches the inside of a metal container, the container will take all of the charge, leaving the object neutral. The excess charge then shows up on the outside surface of the container. Here, our container is the sphere. It is through this effect that the Van de Graaff generator is able to achieve its huge voltages. For the Van de Graaff generator, the belt is the charged object, delivering a continuous positive charge to the sphere.**