Physics

The photoelectric effect is the emission of electrons by substances, especially metals, when light falls on their surfaces. The photoelectric effect will not occur when the frequency of the incident light is less than the threshold frequency as the electrons are unable to gain sufficient energy to overcome the electrostatic barrier of the work function of the metal.

Since we know that electric currents move from a higher potential or a lower potential. Also, electrons move in the direction opposite to electric current. So the electron on the line joining two points A and B will move from lower to higher potential i.e, it will move towards B.

It is launched vertically with an initial speed of 110 ft/sec._x000D_ It will reach maximum height when the speed drops to 0._x000D_ Vo = 110 feet per second_x000D_ ho = 2 feet_x000D_ So, h(t) = -16t^2 +110t +2_x000D_ Take the derivative: h'(t) = 110 -32t_x000D_ The maximum height will be at the inflection when the derivative crosses the x-axis, then h'(t)=0._x000D_ So, set h'(t)=0 and solve for t:_x000D_ 0 = 110 -32t_x000D_ -110 = -32t_x000D_ t = 3.4375_x000D_ t = 3.44 seconds.