Identical point charges (+20 C) are placed at the corners of an ...

[pepyto]

Identical point charges (+20 C) are placed at the corners of an equilateral triangle with sides of 2.0-m length. How much external energy is required to bring a charge of 45 C from infinity to the midpoint of one side of the triangle?
 a. 26 J
  b. 16 J
  c. 23 J
  d. 21 J
  e. 12 J

Question 2

A charge of +3.0 C is distributed uniformly along the circumference of a circle with a radius of 20 cm. How much external energy is required to bring a charge of 25C from infinity to the center of the circle?
 a. 5.4 J
  b. 3.4 J
  c. 4.3 J
  d. 2.7 J
  e. 6.8 J

[SeanoH09]

Answer to Question 1

d

Answer to Question 2

b

[pepyto]

Thank you!

[SeanoH09]

Always glad to help...