Static electricity: like charges push, unlike charges pull

Answer Key - Grade 8 Science Worksheet - Challenge Me

Circle the best answer, or write your answer on the line.

1. 1.

   Two balloons rubbed on Ari's neutral hair gain 3 and 4 electrons. The hair started with 12 − marks. How many − marks does the hair have now?

   5 marks
2. 2.

   Two balloons rubbed on Bo's neutral hair gain 5 and 2 electrons. The hair started with 15 − marks. How many − marks does the hair have now?

   8 marks
3. 3.

   Two balloons rubbed on Esme's neutral hair gain 4 and 3 electrons. The hair started with 14 − marks. How many − marks does the hair have now?

   7 marks

4. Read this first

   Balloon-and-hair pairs (example data)

   pair	extra charges on each	distance apart (cm)
   A	2	10
   B	6	2
   C	6	10
   D	2	2

5. 4.

   In the table of pairs, which pair pulls together hardest, Jun?

   • B
   • C, since charge alone decides it
   • D, since distance alone decides it
   • A, since far apart pulls harder
6. 5.

   Luz moves a rubbed balloon from 2 cm to 10 cm away from the hair. What happens to the pull?

   • It gets stronger
   • It turns into a push
   • It stays the same, since the charge didn't change
   • It gets weaker
7. 6.

   Milo says rubbing a balloon on hair makes new charge. Agree or disagree?

   • Agree: rubbing creates electrons
   • Disagree: electrons just move to the balloon
   • Agree: rubbing magnetizes the balloon and the hair
   • Agree: protons rub off the balloon
8. 7.

   Noah says a balloon sticks to the wall because rubbing makes it a magnet. Agree or disagree?

   • Agree: protons in the wall jump to it
   • Agree: the balloon gets a north pole
   • Disagree: its electric charge pulls the wall
   • Agree: neutral walls can't feel a charge
9. 8.

   Pia says a rubbed balloon can only pull on objects that are already charged. Agree or disagree?

   • Agree: the paper must make its own charge first
   • Agree: the balloon has to touch them
   • Agree: neutral things feel no pull
   • Disagree: neutral paper bits get pulled too
10. 9.

    Ren wants to test whether more rubbing gives a stronger pull on paper bits. Which plan is fair?

    • Use a magnet in place of the balloon
    • Change the rubs and the distance together
    • Change the rubs; keep the distance the same
    • Keep the rubs the same; change the distance
11. 10.

    Two balloons rubbed on hair push each other away, but each one pulls on the hair. Why, Tala?

    • The hair is a weak magnet
    • Rubbing made new charge in the hair
    • The balloons lost their charge
    • The balloons are both −; the hair is +