Chapter 19 - Electric Forces and Fields

Question 1

what is an easy way to give objects a net charge

Answer 1

rubbing

Question 2

how do you get charge differences by rubbing

Answer 2

dislodged electrons can cling to one object, leaving the 2 objects with equal and opposite net charges

Question 3

what does it mean for metal to be a conductor

Answer 3

electrons are relatively free to move about

Question 4

what does it mean for an object to be an insulator

Answer 4

electrons are not free to move about

Question 5

what is induced polarization

Answer 5

induced charge separation

Question 6

what kind of object can get induced polarization

Answer 6

conductors AND insulators

Question 7

what does it mean that insulators can do induced polarization

Answer 7

there can be attraction between a neutral and any charged object!!! (tiny dipole on molecular scale)

Question 8

what is coulombs law

Answer 8

magnitude of force between two point charges

Question 9

when should you put a negative in front of coulombs law

Answer 9

if the charges are attracted

Question 10

when should you put a positive in front of coulombs law

Answer 10

if the charges are repulsed

Question 11

how do you find the Fnet acting on charge q

Answer 11

you do a vector sum of individual forces

Question 12

why can we say that each object is just a point

Answer 12

because the size of object &laquo_space;relevant distances

Question 13

is electric field scalar or vector + why

Answer 13

vector because it has a magnitude and direction that may vary with the location in the field

Question 14

what does the magnitude of E represent

Answer 14

force per unit charge exerted on q at that location

Question 15

how do you determine the direction of E

Answer 15

its the direction that a +ve charge would experience at that location

Question 16

how do you show that an electric field is strong with lines

Answer 16

when they are closer together, it means that they are stronger

Question 17

what is proportional to the magnitude of the charge

Answer 17

the total # of electric field lines

Question 18

how do you find the net E field at some location with multiple charges present

Answer 18

use vector addition

Question 19

where do the lines begin and end when drawing electric field lines

Answer 19

start on + and end on -

Question 20

what is another way to call electric field lines

Answer 20

lines of force

Question 21

what is another way to call lines of force

Answer 21

electric field lines

Question 22

do lines of force ever cross

Answer 22

no

Question 23

do electric field lines ever cross

Answer 23

no

Question 24

what is the direction of force of a + charge in an electric field

Answer 24

in the same direction as the electric field lines

Question 25

what is the direction of force of a - charge in an electric field

Answer 25

in the same opposite as the electric field lines

Question 26

what is a uniform electric field

Answer 26

when the electric field in a region is uniform if the magnitude and direction are constant everywhere within the region (parallel and evenly spaced lines)

Question 27

if a conductor carries a net charge, where will excess charges go

Answer 27

they will reside on the surface

Question 28

if a conductor carries a net charge, where will E field lines be

Answer 28

emerge perpendicular to the surface

Question 29

if a conductor carries a net charge, what is the E inside the conductor

Answer 29

0 unless there is a charged object inside the conductor

Question 30

if a conductor carries a net charge, where do charges tend to bunch up + what does this lead to

Answer 30

near points and sharp edges, leading to a strong electric field