Identical point charges (+50 mC) are placed at the corners of a square with sides of 2.0-m length. How much external energy is required to bring a fifth identical charge from infinity to the geometric center of the square?
a. 41 J
b. 16 J
c. 64 J
d. 10 J
e. 80 J
C
You might also like to view...
One kilogram is the same as
a. 1000 g. b. 1/1000 kg. c. 10,000 g. d. 0.001 g.
Latent Heats: If you add 700 kJ of heat to 700 g of water originally at 70.0°C, how much water is left in the container? The latent heat of vaporization of water is 22.6 × 105 J/kg, and its specific heat capacity is 4186 J/kg ? K.
A. 429 g B. 258 g C. 340 g D. 600 g E. none
Potential of Point-Charges: Point charges +4.00 ?C and +2.00 ?C are placed at the opposite corners of a rectangle as shown in the figure. What is the potential at point A, relative to infinity, due to these charges? (k = 1/4??0 = 8.99 × 109 N ? m2/C2) 
A. 0.899 kV B. 8.99 kV C. 89.9 kV D. 899 kV E. 8990 kV
A main difference between gravitational and electric forces is that electric forces
A) attract. B) repel or attract. C) obey the inverse-square law. D) act over shorter distances. E) are weaker.