ELECTROSTATIC
QUIZ after movie


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QUIZ -  20 questions - 5 points per questions - yes I grade.
1) The Greeks used _____________ for their electrostatic experiments (from a tree)
When the Greek ladies were bored during parties, they would rub their jeweleries made of _________ and
would touch frogs for fun. Frogs would jump like crazy. What do you think the frog was experiencing ?

2) What is the origin of the name electricity ? _____________ = elektron in Greek.


3) What is the famous experiment of Ben Franklin that proved that lighting was electricity ?


4) What is a leyden jar?

5) Why Franklin was almost right when explaining electricity using one fluid model ?
What was wrong?


6) Is it the positive charges or the negative charges that are moving?

7) What is the difference between insulator and conductor?

8) lightning occurs when there is a charge ___________ due to friction.

9) rub an ebonite rod with fur and a glass rod with silk, do they collect like charges or unlike charges ? How do you know (how to find out )?

10)  Look at the electron affinity chart

Hold electrons tightly
Sulfur
brass
copper
ebonite
wax
silk
lead
fur
wool
glass
hold electrons lightly

If you rub glass with wool, which one becomes + ? ___________________
if you rub an ebonite rod with fur, which one is  negatively charged ? ______________
What about silk and copper ?_______________________
silk and glass ?___________________________________________

11) Which 2 materials would you use to collect more charges on each on them ?

12) What is the modern device that collect charges now day ? (it used to be the leyden jar)

13) Which part of a camera uses a capacitor ?

14) In a car, what do we use to ignite the fuel ?

15) THe build up of electric charges due to friction explain ____________ phenomena
: the electric charges are separated in a first step (the ebonite rod collects ______ charges and
the wool collects ___________ charges). In a second step the charges combine again producing
a __________.

16) The separation of positive and negative charges always means that ____________ have been transferred. (neutrons? quarks ? electrons ? protons ?)

17) the law of conservation of charge states that in an isolated system, the total charge of the system _____________________. charges within the system can be transfered from one object to another,but charge is neither __________nor _______

18) Question 17)  means: total charge before = total charge after or
Qtotal before = Qtotal after (law of conservation of charges).
A) You have a rod and a cloth. They are both uncharged. So Qtotal before = ______.
You rub them together such as the rod acquires a charge of  Q1 = + 10-6 C (or E6 C) .
The cloth acquires a charge of Q2. Because of conservation of charge
Qtotal after = Qtotal before =_____ = Q1 + Q2 (sum of charges). So Q2 = _______. 

B) 2 identical spherical spheres, A and B, carry charges of QA = 6 microcoulombs (6 10-6C or 6E-6) and QB =  -2 microcoulombs (-2 10-6C pr -2E-6C), respectively. Qtotal before = QA + QB =  _______.  If these spheres touch, what will be the resulting charge on A ? (try without hint)
(hint: Total Q before = total Q after. And the 2 spheres are identical, they should carry the same amount of charge
after they were in contact. So QA after = QB after  )
______________________________________________________________________________________--

V)  FILL THE BLANKS - This is our next quiz

1) Fill blanks:
An atom is made of the __________ in the center and a cloud of __________ around.
The nucleus is __________ charged and the electrons are ____________ charged.
The  diameter of the nucleus of H is about 10-12 cm. or a millionth of a millionth of 1 cm. ( __________________ in standard notation)
It means you have to divide 1 cm in to 1 _____________________ parts to get the size of a nucleus.
The diameter of the whole atom (from center to cloud) is 10-8 cm. THis is ______ billionth of 1 centimeter. (1 billionth = 10-9)
It means you need to divide 1 cm into  1__________________ parts to vizualise the size of an atom. (not possible with the naked eye).
The atom is ______________ times greater than the nucleus. (find ratio 10-8/10-12). This is  _____________ orders of magnitude.
(hint: 100 is 2 orders of magnitude )
If a nucleus were to be of a size of a marble (1cm), then the electrons would be at a distance of ___________ cm = _________ m
that is _________ meter sticks away. Or ________ miles away (1mile=1600m).
This is like one block away. (South-North in New York city)

2) Fill blanks:
remember rubbing glass +silk = makes the glass positive and the silk negative. (the silk takes the_________, it has more affinity for them)
                  rubbing ebonite (kind of plastic)  + car fur = makes ebonite negative and the fur positive
(the ebonite takes the ________, it has more  ________ for them)

A conductor have a small amount of ___________ that are free to move around, like a fluid can flow from a high position to a lower one.
This model of electrons, behaving like a fluid, was introduced by Benjamin Franklin who didn't know about electrons.

In an insulator the electrons are attached to their atoms and are not free to flow. However, if you rub insulators, they can lose electrons
(they become _______ ________) or gain electrons (they become _________ __________) . Eve

n though  electrons can not flow in an insulator,
they can be taken away from an insulator or added to an insulator. An insulator can ________ electrons  or __________ electrons.

3) A)Like charges __________, unlike charges _________. When ebonite  is rubbed with wool, some ________ leave the _________
and move to the ________ so the ebonite becomes _______ charged and the wool is left __________ charged.
B) A negatively-charged object attracts a piece of paper because it _________ electrons away from the surface of the paper.
This leaves the surface of the paper ________ charged so that it is _______- to the object. These separated charges
are called p_________ charges.
C) In a gold-lead electroscope, the leaf rises because like charges _________
D) conductors (unlike _________ ) allow _________ to travel through them.

3) A)What is meant by saying charge is conserved ?
B) What part of an atom is negatively charged and what part of the atom is positively charged?
C) What kind of charges does an object acquire when electrons are stripped from it.