Transcript 10.2 Charging By Contact and By Induction (Pages 411-416) Homework: Page 417 # 2-5, 7, 8 Key Concepts: (Page 417) • An electroscope is a.

10.2 Charging By Contact and By
Induction
(Pages 411-416)
Homework: Page 417 # 2-5, 7, 8
Key Concepts: (Page 417)
• An electroscope is a device that is used to
detect the presence of an electric charge.
• There are three laws of electric charges: Like
charges repel; Opposite (unlike) charges attract;
Neutral objects and charged objects are
attracted to each other.
• Copy down Figure 10.12 (p. 413)
• An object that is charged by contact has the
same type of charge as the charging object.
• An electric force between two objects is
transmitted by an electric field.
• An induced charge separation is the movement
of electrons in a substance, caused by the
electric field of a nearby charged object.
• Watch This!
What is an electroscope?
• An electroscope is a device that
detects the presence of an electric
charge
2. Compare & Contrast –
Charging by contact
• Takes place when contact is made
between a neutral object and an object
that is charged
• An object that becomes charged by
contact always gets the same type of
charge that is on the object that charges it
– Ex. Ball (negatively charged) comes in
contact with rod (neutral, no charge)  rod
becomes negatively charged
Charging by friction
• Two different materials
• One material has a stronger attraction to
electrons (which are negatively charged)
than another material
• Therefore, electrons are pulled off the
material that has the weaker attraction for
them
• Both materials become charged due to an
excess or shortage of electrons
Charging by induction
• The movement of electrons in a substance,
caused by the electric field of a nearby charged
object (positive or negative) without direct
contact between the substance & the object
• The electric field of the charged object produces
a force on the neutral object
• Example:
– A Rod (negative) comes in contact with a ball
(neutral) and the electrons in the ball move away from
the rod (because similar charges repel)
– This creates a positive side to the ball which becomes
attracted to the negative rod & causes it to move
towards the rod