Chapter - 17 (Static electricity) Flashcards

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1
Q

What are the 2 types of charges?

A
  • Positive
  • Negative
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2
Q

what happens to opposite charges?

A

attract

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3
Q

What happens to like charges?

A

Repel

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4
Q

What is electric charge measured in?

A

Coulombs (C)

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5
Q

How is electrostatic repulsion caused?

A

When the charges are the same as reach other (repulsion)

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6
Q

How do insulating solids get a charge?

A
  • by friction to transfer electrons
  • by removing electrons that have a negative charge are left with a positive charge
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7
Q

What is the process for producing an electrostatic charge?

A
  1. Suspend insulating material using a cradle and a length of string so that the material can rotate softly
  2. Rub one end of material using a cloth (in order to give it a charge)
  3. Take a 2nd piece of insulating material and charge that by rubbing with a cloth
  4. Hold the charged end of the 2nd piece end of First piece
  • if the material piece rotates away (repelled) then materials have the same charge
  • if the First piece move towards (is attracted) then they have opposite charges
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8
Q

What does a charged object create?

A

Electric field

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9
Q

How is electric field shown?

A

Field lines point away from positive charges towards negative charges

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10
Q

What does the direction of force refer to?

A

A positive charge, it is always electrons that are free to move according to that force.

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11
Q

What does the strength of an electric field depend on?

A

Distance from the object creating the field.

  • field is strongest close to the object (lines are close)
  • field is weaker away from the charged object (lines are further away)
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12
Q

What do objects in electric field experience?

A

Electric field

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13
Q

What do the direction of the force depend on?

A

Charges are same or opposite

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14
Q

What 2 options can the force be?

A
  1. Attractive
  2. repulsive
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15
Q

What happens to the forces if charges are the same?

A
  • (negative and negative) or (positive and positive)
  • repulsive
  • 2nd object will move away from the charge creating field
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16
Q

What happens if the charges are opposite?

A
  • (negative and positive)
  • Attractive
  • object move towards charge creating field
17
Q

What does the size of force depend om?

A

Strength of field at that point

18
Q

What does it mean when the force becomes stronger?

A

The distance between two charged objects decreases

19
Q

What does it mean when the force becomes weaker?

A

distance between 2 charged objects increases

20
Q

What should we note about the field lines?

A

Go from positive to negative

Same direction as the direction of the force on a positively charged particle at a point.

21
Q

What is the electric field between two parallel plates?

A

uniform electric field.

22
Q

What are the properties of electric field lines?

A
  • directed from positive to negatuve plate
  • parallel
  • straight lines
23
Q

How are field lines around a charged conducting sphere?

A
  • Symmetrical
  • they repel (charge same)
  • charges on surface will be evenly spread
  • surface is conducting allowing them to move
24
Q

How can the field line be demonstrated?

A

Van der Graff Generator

25
Q

How can the field lines be demonstrated in schools?

A
  • small pieces of paper
  • polystyrene beads
  • aluminum foil containers
26
Q

What is main difference in conductors and insulators?

A

Conductors - allow charge carrier to move freely

Insulator - do not allow charge carriers to move

Due to their internal structures.

27
Q

Define conductor

A

A material that allows charge (usually electrons to flow through it)

28
Q

What are examples of conductors

A

Silver
Copper
aluminum
Steel

29
Q

What are the conductors made up of?

A

Positively charged metal ions with their outermost electrons delocalized.

30
Q

Why do metals conduct electricity?

A
  • current is the rate of flow of charged particles
  • more easily the electrons are able to flow, the better the conductor.
31
Q

Define insulator.

A

Insulator is a material that has no free charges and does not allow the flow of charges.

32
Q

What are examples of insulators?

A
  • Rubber
  • plastic
  • glass
  • wood
33
Q

What can be used to investigate electrical conductors and insulators?

A

Gold leaf electroscope (GLE)

34
Q

What does the GLE consist of?

A
  • metal plate attached to one end of metal rod
  • other end is a thin leaf of gold foil
  • rod held by insulating collar inside a box with glass sides, allowing gold leaf to be seen and protected from draughts
35
Q

What happens when the GLE is charged?

A
  • plate, rod, and gold leaf have same charge
  • they repel and leaf sticks out the side
  • when rod and leaf are discharged, (are neutral) the Leafs hang down.
36
Q

How do we test the electrical conductors and insulators?

A
  • charge the plate of GLE so that gold leaf stands clear of the rod
  • carefully touch the plate of GLE with items being tested
37
Q

What should you do after you test for electrical conductors and insulators?

A

Record the observation:

  1. Leaf falls: Material is a good conductor
  2. Leaf remains in place: Object is poor conductor (good insulator)
  3. Leaf falls slowly: Material is a poor conductor.
38
Q

What is an alternate way to test for electrical conductors and insulators?

A

An electronic charge detector