Electricity and Magnetism Answers

An electron of charge e is moving at a constant velocity u, along the x-axis. It enters a region of constant electric field E, which is pointing perpendicular to the x-axis. The electron moves in a parabola. Which of the following represents the focal length of the parabola? Neglect any effects due to gravity. (for a parabola of type x2=4ay, a is the focal length)

Two point charges are separated by a distance r. If the separation is reduced by a factor of 1.5, by what factor does the electric force between them change? 

Two particles with electric charges Q and -3Q are separated by a distance of 1.2 m.

(a) If Q = 4.5C, what is the electric force between the two particles?

(b) If Q= -4.5 C, how does the answer change? 

A thin sheet of mica is inserted between the plates of a plane capacitor. What pressure will act on this sheet when the intensity of the electric field is 10 kV/cm?

How many coulontos of charge move across a 120 V source when 1440 J of energy is

required?

A sphere of radius R carries a charge of volume charge density ρ ar, where a is a constant and r denotes the distance from the centre of the sphere. Calculate the total charge enclosed by the sphere and the electric field at points lying inside and outside the sphere. 

19.Find the capacitance of Earth. The radius of the Earth is 6,400 km By how much will the Earth's potential change if it receives a quantity of electricity equal to 1C?

19. Find the capacitance of the Earth .the radius of the Earth is 6,400 km.By how much will the Earth`s potential chance if it receives a quantity of electricity equal to1C?

Find the potential drop along a copper wire 500 m long and 2 mm in diameter if the current in it is equal to 2 A. Determine the potential drop in resistors. ρ(copper)=1.68×10−8 (Ω·m)Energy of charged capacitor.

. Determine the force (per unit area) which two like-charged infinitely long planes having the same charge surface density of 3 x 10^-8 C/cm2 will repel each other with