An infinitely long positively charged wire with a uniform linear charge density +λ is parallel to the y axis of a Cartesian coordinate system and passes through the x axis at x=−d. At the origin, the electric field due to this charged wire has magnitude E0 and is directed to the right along the positive x axis. A second infinite charged wire, parallel to the first and with a uniform linear charge density, passes through the x axis at x=+3d. The vector sum of the electric field at the origin due to the two lines of charge has magnitude 2E0.

What is the linear charge density of the second charged wire?

The answer is 9λ and -3λ which but i dont understand how they got that answer

Consider the particle-in-a-box problem in 1d. a particle with mass m is confined to move freely between two hard walls situated at x = 0 and x = l. the potential energy function is given as (a) describe the boundary conditions that must be satisfied by the wavefunctions ψ(x) (such as energy eigenfunctions). (b) solve the schr¨odinger’s equation and by using the boundary conditions of part (a) find all energy eigenfunctions, ψn(x), and the corresponding energies, en. (c) what are the allowed values of the quantum number n above? how did you decide on that? (d) what is the de broglie wavelength for the ground state? (e) sketch a plot of the lowest 3 levels’ wavefunctions (ψn(x) vs x). don’t forget to mark the positions of the walls on the graphs. (f) in a transition between the energy levels above, which transition produces the longest wavelength λ for the emitted photon? what is the corresponding wavele

In positive numbers less than 1, the zeros between the decimal point and non zero are significant

An object is 10 cm from the mirror, its height is 1 cm and the focal length is 5 cm. what is the image height? (indicate the object orientation by including the + or - sign with the answer.) hi = cm +1 -1 +10 -10