1 Electrostatics and Current Flashcards
Two insulating materials are rubbed together.
They are charged by friction.
Which particle is transferred between them?
Electrons
Charge does not flow easily through what sort of material?
insulators
eg plastic or wood
What is the current if 7200 C passes in 1 hour ?
I = Q/t
time must be in seconds
1 hour = 1 x 60 x 60 = 3600 secs
I = 7200 C/ 3600 s
I = 2 A
What is the current if 360 C passes a point in a circuit in 2 min?
I = Q/t
time must be in seconds
2 min = 2 x 60 = 120 seconds
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?
in the nucleus
If 3nC of electrons were transferred from a cloth to the surface of the rod, what is the charge on the rod?
- 3 nC
negative charge as the rod has gained electrons
What happens when two negatively charge balloons hang side by side?
They 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 means x 10-9
example 10 nC = 10 x 10-9 C
What is the definition for current?
Current = the rate of flow of charge
I = Q/t
Only electrons are transferred when objects are charged by friction. Why?
Electrons are located in the outer shells of an atom so are easily removed.
But protons are located in the nucleus at the centre of the atom so cannot be removed easily.
If 5 mA flows for 10 minutes, how much charge flows?
Q = I x t
time must be in seconds
t = 10 x 60 = 600 seconds
Current must be in amps
I = 5 mA = 5 x 10-3 A
Q = 5 x 10-3 x 600 = 3C
A negatively charged polythene rod is scraped across a gold leaf electroscope. The gold leaf rises.
Look at the diagram to explain why?
What would you observe if the same thing was done with a postive acetate rod?
![](https://s3.amazonaws.com/brainscape-prod/system/cm/276/107/048/q_image_thumb.jpg?1509026367)
The gold foil rises as it is repelled from the central post as like charges repel.
Same would happen for both acetate and polythene but with opposite charges.
![](https://s3.amazonaws.com/brainscape-prod/system/cm/276/107/048/a_image_thumb.jpg?1509026301)
What is the symbol for an ammeter and how is it connected in the circuit?
An ammeter is connected in series
![](https://s3.amazonaws.com/brainscape-prod/system/cm/276/107/052/a_image_thumb.jpg?1509025351)