Question

Form 2: Page 6 A point charge Q is placed at the origin at r=0. What is the electric potential V at a distancer from this point charge? a. kQ/r2 b. kQ²/1 c.-k / d. -kQ/ kor An electric field in one dimension varies as E(x)=CX The potential is zero at x = 0 What is the potential V(x)? a-CX2/2 b. 2CX-32/3 c. -2CX32/3 d. -2CX 2 Cx12/3 18. The electric field vector between two charges of - and in one-dimension: points from the positive to the negative charge, and is parallel to the lines of constant potential points from the positive to the negative charge, and is perpendicular to the lines of constant potential points from the negative to the positive charge, and is parallel to the lines of constant potential & points from the negative to the positive charge, and is perpendicular to the lines of constant potential Ve it has no direction since the electric field is a scalar A capacitor with capacitance C is charged to a voltage V. How much energy is stored in this capacitor? %CV2 b. CV C. & CV d. CV2 e V/C 19. 20. I insert a material with dielectric constant K into the space between the parallel plates of a capacitor such that the dielectric fills the volume between the plates. The plate area is A, and the separation between the plates is d. What is the capacitance of this device, ignoring the fringe fields near the edges? @ K € A/d b. & A/d c. A/(Kd) d. zero

Answer 1

16. The electric potential at a distance R from a charge Q is given as

V= KQ/R E) is correct

17. Ex = CX

-dV/dX = CX

V - 0 = -1/2CX²

^{a is correct}

18. Electric field is away from positive charge and towards the negative charge

and is perpendicular to electric field lines (b) is correct

19. Energy = 1/2CV² a) is correct

20. The capacitance is K times the usual , C = KeA/d so a) is correct