Electrostatics and Current Flashcards
When two insulating materials are rubbed together, what particle could be transferred between them?
An electron would transfer from one insulator to the other.
What sort of material will not allow charge to flow through it easily?
an insulator such as plastic or wood
A polythene rod is charged by friction and scraped across a nanocoloumbmeter, what charge will the nanocoulombmeter adopt?
Nanocoulombmeter becomes negatively charged
Explanation
Polythene gains electron from the cloth to become negatively charged
This negative charge transfers to the nanocoulombmeter when electrons transfer from the rod to the nanocoulombmeter
What is the current if 7200 C passes in 1 hour ?
I = Q/t
I = 7200 C/ (1 x 60 x 60) s
I = 7200 C/ 3600 s
I = 2 A
time must be in seconds!
What is the current if 360 C passes in 2 min?
I = Q/t
I = 360 C/ (2 x 60) s
I = 360 C / 120s
I = 3 A
Name three uses of electrostatics
- electrostatic smoke removal from chimneys
- photocopier
- inkjet printer
- electrostatic paint sprayer
- electrostatic crop sprayer
Where are neutrons located in an atom?
the nucleus
What charge would a rod adopt if 3nC of electrons were transferred from a cloth to the surface of the rod?
- 3 nC
Describe what a gold leaf electroscope is.
A gold leaf electroscope is used to study electrostatic charge
It has a metal plate at the top which is connected to a metal rod encased in a glass box. A piece of very thin gold foil is glued to the side of the metal rod.
What is an induced charge?
When a neutral object has a separation of charge within itself.
Electrons move from one side of the object to the other.
The side with more electrons is negatively charged
The side with fewer electrons is positively charged.
Overall the charge is neutral- charge is only displaced within the object itself
What would happen in two negatively charge balloons were hung side by side?
They would repel because like charges repel
What is the current if 100 C passes in 200s ?
I = Q/t
I = 100 C/ 200 s
I = 0.5 A
What does the prefix nano stand for in 10 nC
nano is 10-9 or 10nC = 10 x 10-9 C
What is the definition for current?
The rate of flow of charge
OR
The number of coulombs passing a point in a circuit per unit time
Explain why only electrons are transferred when objects are charged by friction.
Electrons are located in the outer shells of an atom and are easily removed.
However, protons are located in the nucleus at the centre of the atom and are tightly bound.
If 10 mA flows for 10 minutes, how much charge flows?
Q = I x t
Q = 0.01 A x (10 x 60s ) = 6C
time must always be converted into seconds
current must be in amps so milli is 10-3
What is the current if 360 C passes in 2 min?
I = Q/t
I = 360 C/ (2 x 60) s
I = 360 C / 120s
I = 3 A
What is the current if 100 C passes in 200s ?
I = Q/t
I = 100 C/ 200 s
I = 0.5 A
A negatively charge polythene rod is scrapped across a gold leaf electroscope. The gold leaf rises.
What would you observe if the same thing was done with an acetate rod?
The gold leaf would rise just the same as it did with the polythene rod.
The gold foil is repelled from the central post in both cases as negative and negative repel the same as positive and positive charges.
A polythene rod is charged by friction and scraped across a nanocoloumbmeter, what charge will the nanocoulombmeter adopt?
Nanocoulombmeter becomes negatively charged
Explanation
Polythene gains electron from the cloth to become negatively charged
This negative charge transfers to the nanocoulombmeter when electrons transfer from the rod to the nanocoulombmeter
What does the prefix micro stand for in 100 uA
micro is 10-6 or 100 uC = 100 x 10-6 C
Explain how a gold leaf electroscope works.
When it is charged, both the rod and leaf adopt the same charge and the gold leaf is repelled from the rod and rises.
The greater the charge, the greater the repulsion the further the gold foil rises.