Charging By Friction

1
Charging By Friction

• When two objects are rubbed together, the
  molecules are close enough together that the
  electrons from one substance can move onto the
  other substance.

2

• The substance that gains extra electrons becomes
  negatively charged, while the substance with
  fewer electrons becomes positively charged.
• The more rubbing, the more transfer, the greater
  the charge.

3
The Electrostatic Series

• As previously discussed, some objects hold their
  electrons tighter than others.
• The electrostatic series ranks objects by how
  easily they let go of e- during friction.

4

• Substances that let go easily are on top and
  become positively charged.
• Substances on the bottom hold tight and take on a
  negative charge.
• The further the substances are apart, the more
  charge that it produced.

5

• Acetate
• Glass
• Wool
• Fur or hair
• Silk
• Aluminium
• Cotton
• Paraffin wax
• Plastic
• Rubber
• Gold
• -

6
Example

• When clothes are put in a dryer without fabric
  softener, they rub against each other and become
  charged.
• Which item would take on which charge if

7

• Cotton socks are dried with a wool sweater?
• -
• b) A wool sock is dried with a silk shirt?
• -

8

• When you comb your hair with a plastic comb, your
  hair becomes statically charged.

9

• What is the charge on your hair?
• On the comb?
• -

10

• What could you use to make a comb that would
  produce less charge?
• Hair Aluminium
• Comb - Acetate

11
Charging By Contact

• Electric charge can be transferred between
  objects just by touching them together.
• Charging by conduction occurs when a charged
  object touches a neutral object.

12

• A few electrons move from one object to the other
  (electrons try to move where they are needed).
• As a result, both objects end up with the same
  charge.

13
Charging By Introduction

• Neutral objects are attracted to charged objects.
  
• In fact, a charged object can induce a charge in
  another object.

14

• The neutral object never actually gains or loses
  any electrons.
• When the charged object is brought close, the
  electrons move slightly in the uncharged object.

15

• So if a positive object in brought near, the
  electrons are attracted and move closer.
• If the charge is negative, the electrons are
  repelled and move away.

16
Discharging An Object

• If you connect an electrical device or something
  with a charge to the earth or the ground, then
  the extra charges get transferred into the Earth.
• Since the Earth is so large, it can accept a lot
  of electrons without having much effect.
• This is called grounding an object.