An object of mass m = 3.88 g and charge q = +43.0 microcoulombs is attached to a string and placed in a uniform electric field that is inclined at an angle of 28.4° with the horizontal, as shown in the figure below.
walk1974.gif
the object is in static equilibrium when the string is horizontal. calculate the magnitude of the electric field.
calculate the tension in the string.

Unpolarized light of intensity i_0=750w/m^2 is incident upon two polarizers. after passing through both polarizers the intensity is i_2=280w/m^2. (a) what is the intensity of the light after it passes through the first polarizer in w/m^2? (b) write an equation for the angle between the polarizers in terms of the initial (i_0) and final (i_2) intensities. (c) find the angle between the polarizers in degrees.