A square is 1.0 m on a side. Point charges of +4.0 C are placed in two diagonally opposite corners.
In the other two corners are placed charges of +3.0 C and -3.0 C. What is the potential (relative to infinity) at the midpoint of the square? (k = 1/40 = 9.0 109 N m2/C2 )
A) 1.0 106 V B) infinite C) 1.0 105 V D) 0 V E) 1.0 104 V
Question 2
An electric current through a tungsten filament maintains its temperature at 2800 K. Assume the tungsten filament behaves as an ideal radiator at that temperature.
If the radiating area of the filament is 2.0 10-6 m2, at what rate does it radiate energy? ( = 5.670 10-8 W/m2 K4, Wien displacement law constant is 2.90 10-3 m K)
A) 11.5 W B) 7.0 W C) 8.5 W D) 5.5 W E) 10 W