1 Electrostatics and Current Flashcards

1
Q

When two insulating materials are rubbed together, which particle is transferred between them?

A

An electron** would **transfer from one insulator to the other.

2
Q

What sort of material does not allow charge to flow through it easily?

A

an insulator such as plastic or wood

3
Q

A polythene rod is charged by friction and scraped across a nanocoloumbmeter, which charge will the nanocoulombmeter adopt?

A

Nanocoulombmeter becomes negatively charged

Explanation

Electrons transfer from the cloth to the polythene rod. The rod becomes negatively charged

This electrons transfers from the polythene rod to the nanocoulombmeter

4
Q

What is the current if 3600 C passes in 1 hour ?

A

Q=It

I = Q/t

I = 3600 C/ (1 x 60 x 60) s

I = 3600 C/ 3600 s

I = 1 A

time must be in seconds!

5
Q

What is the current if 360 C passes a point in a circuit in 2 min?

A

Q=It

I = Q/t

I = 360 C/ (2 x 60) s

I = 360 C / 120s

I = 3 A

6
Q

Name three uses of electrostatics

A
1. electrostatic smoke removal from chimneys
2. photocopier
3. inkjet printer
4. electrostatic paint sprayer
7
Q

Where are neutrons located in an atom?

A

the nucleus

8
Q

What charge would a rod adopt if 3nC of electrons were transferred from a cloth to the surface of the rod?

A
• 3 nC
9
Q

Describe what a gold leaf electroscope is.

A

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.

10
Q

What is an induced charge?

A

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

11
Q

What would happen if two negatively charge balloons were hung side by side?

A

They would repel because like charges repel

12
Q

What is the current if 100 C passes in 200s ?

A

Q = It

I = Q/t

I = 100 C/ 200 s

I = 0.5 A

13
Q

What does the prefix nano stand for in 10 nC

A

nano is 10-9

or

10nC = 10 x 10-9 C

14
Q

What is the definition for current?

A

The rate of flow of charge

OR

The number of coulombs passing a point in a circuit per unit time

15
Q

Explain why only electrons are transferred when objects are charged by friction.

A

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.

16
Q

If 10 mA flows for 10 minutes, how much charge flows?

A

Q = I x t

Q = 10x10-3 A x (10 x 60s ) = 6C

time must always be converted into seconds

current must be in amps so milli is 10-3

17
Q

What is the current if 100 C passes in 200s ?

A

Q=It

I = Q/t

I = 100 C/ 200 s

I = 0.5 A

18
Q

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?

A

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 both the post and the gold leaf have the same charge.

19
Q

A polythene rod is charged by friction and scraped across a nanocoloumbmeter, what charge will the nanocoulombmeter adopt?

A

Nanocoulombmeter becomes negatively charged

Explanation

Polythene gains electron from the cloth to become negatively charged

The electrons transfers from the polythene rod tot the nanocoulombmeter

20
Q

What does the prefix micro stand for in 100 uA

A

micro is 10-6

or 1

00 uC = 100 x 10-6 C

21
Q

Explain how a gold leaf electroscope works.

A

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.

22
Q

What is the symbol for an ammeter and how is it connected in the circuit?

A

An ammeter is connected in series

23
Q

A acetate rod is charged by friction and scraped across a nanocoloumbmeter, what charge will the nanocoulombmeter adopt?

A

Nanocoulombmeter becomes positively charged

Explanation

Acetate loses electron to the cloth to become positively charged

Electrons transfer from the nanocoulombmeter to the rod, leaving the nanocoulombmeter positive.

24
Q

What does the prefix milli stand for in 65 mA

A

milli is 10-3

or

65 mC = 65 x 10-3 C

25
Q

If 100 A flows for 10 s, how much charge passes?

A

Q= I x t

Q = 100 A x 10 s = 1000 C

26
Q

What equation links charge, current and time?

A

Charge = current x time

Q = It

OR Current = charge / time

I = Q/t

27
Q

I am the rate of flow of charge. What am I?

A

Current

28
Q

If 4 A flows for 2 minutes, how much charge flows?

A

Q = I x t

Q = 4 A x (2 x 60s ) = 480C

time must always be converted into seconds

29
Q

What is the current if 1000 C passes in 500s?

A

I = Q/t

I = 1000 C/ 500 s

I = 10C / 5s

I = 2 A

30
Q

Where are protons located in an atom?

A

the nucleus

31
Q

A polythene rod is rubbed with a cloth. What happens?

A

Electrons transfer from the cloth to the rod.

The polythene rod becomes negatively charged

The cloth becomes postively charged

32
Q

Which sort of material allows charge to flow through it?

A

conductor such as a metal

33
Q

What is the relative charge of an electron?

A

-1

34
Q

What charge would a rod adopt if 5nC of electrons were transferred from its surface to a cloth?

A

+ 5 nC

35
Q

What would happen if two positively charge rods were hung side by side?

A

The would repel because like charges repel

36
Q

How can a charged object be discharged?

A

Earth it. Connect a wire conductor from the object to a stake in the ground.

37
Q

What is the relative charge of a proton?

A

+1

38
Q

What is the relative charge of neutron?

A

0

39
Q

An acetate rod is rubbed with a cloth. What happens?

A

Electrons transfer from the rod to the cloth.

The acetate rod becomes positively charged

The cloth becomes negatively charged

40
Q

Where are electrons located in an atom?

A

shells

41
Q

What equation links current, charge and time?

A

Charge = current x time

Q=It

42
Q

What is the current if 1000 C passes in 500s?

A

I = Q/t

I = 1000 C/ 500 s

I = 10C / 5s

I = 2 A

43
Q

What charge would a rod adopt if 5nC of electrons were transferred from its surface to a cloth?

A

+ 5 nC

44
Q

Name three dangers of electrostatic charge

A
1. Refueling cars or aircraft
2. explosion of dust or fine powder in industry
3. Lightning from charge build up in clouds
4. Spark in operating theatre- explosion of oxygen
45
Q

What can we use to measure charge?

A

A nanocoulombmeter

46
Q

How can we reduce the electrostatic force acting on the objects below?

A

Move them further apart OR decrease their charge.

47
Q

What would happen if a negatively charge rod and a positively charge rod were hung side by side?

A

The would attract because unlike charges repel