topic 11 Flashcards
a student rubs a plastic comb with a dry cloth to give the comb a positive electric charge. figure 6 shows the charged plastic comb picking up small pieces of paper.
explain how rubbing the comb with a dry cloth gives the comb a positive electric charge.
friction between cloth and comb results in a transfer of electrons onto cloth and these electrons have a negative charge (leaving excess positive charge on comb)
a student rubs a plastic comb with a dry cloth to give the comb a positive electric charge. figure 6 shows the charged plastic comb picking up small pieces of paper.
explain how the positively charged plastic comb picks up the small pieces of paper
a negative charge is induced on the part of the paper closest to the comb. opposite charges attract so it picks up paper
figure 1 shows a paint sprayer, some paint sprayers give the paint drops a positive charge as they leave the sprayer. the paint drops have a positive charge because the sprayer..
A) removes electrons from the paint drops
B) adds electrons to the paint drops
C) removes protons from the paint drops
D) adds protons to the paint drops
A) removes electrons from the paint drops
figure 2 shows the spray pattern from two different paint sprayers.
sprayer x doesnt charge the paint drops. sprayer y gives the paint drops a positive charge. explain how charging the paint drops changes the shape of the spray pattern
like charged drops are repelling each other so spray is wider from sprayer
figure 2 shows the spray pattern from two different paint sprayers.
sprayer y is used in a factory to paint a metal object. the object hangs by a metal wire that is connected to earth.
explain why a metal wire is used to connect the object to earth
metal wire can conduct electrons so it prevents positive charge accumulating on the object
a student has a rubber balloon tied to a long piece of cotton thread. the student gives the balloon an overall electrostatic charge.
describe one way the student could give the balloon an overall electrostatic charge
rub the balloon with a cloth
the student gives the balloon an overall negative charge. which of these explains why the overall charge on the balloon is negative?
A) negative charge has been removed from the balloon
B) negative charge has been added to the balloon
C) positive charge has been removed from the balloon
D) positive charge has been added to the balloon
B) negative charge has been added to the balloon
the student charges another balloon on a long thread.
explain how the student could show that the two balloons have the same type of charge
they could use a method of handling them without discharging them like bringing balloons near each other and repulsion can be observed
figure 9 shows a plastic block and a metal disc with an insulating handle. the top surface of the plastic block has a negative charge. the metal disc has no overall electric charge..
a student uses the insulating handle to hold the metal disc above the plastic block. which of these shows how th charge is distributed on the metal disc?
A)
B)
C)
D)
B)
figure 9 shows a plastic block and a metal disc with an insulating handle. the top surface of the plastic block has a negative charge. the metal disc has no overall electric charge..
the student keeps holding the metal disc above the charged plastic block and taps the metal disc with a finger. this earths the metal disc for a short time.
explain why the disc now has an overall positive charge
electrons transfer from the metal disc to the student
draw lines to show the shape and direction of electric field between the metal disc and the plastic block
arrows going downwards from positive to negative
