Voltage on a capacitor

A 12.5 micro Farad capacitor is charged by a 150 volt battery and then is disconnected from the battery. When this capacitor (C1) is then connected to a second (uncharged) capacitor, the voltage on C1 drops to 10 volts. What is the value of C2? (I need a very detailed solution, with every micro-step detailed)

For resistors in parallel configuration, the equivalent resistance is always smaller than the smallest resistor.

Prove: For resistors in parallel configuration, the equivalent resistance is always smaller than the smallest resistor.

Electromagnatism Induction

A metal bar with length L, mass m, and resistance R is placed on frictionless, metal rails that are inclined at an angle (Data) above the horizontal. The rails have negligible resistance. A uniform magnetic fiels of magnitude B is directed downward. The bar is released from rest and slides down the rails. a) Is the direction of the current induced in the bar from a to b or from b to a? b) What is the terminal speed of the bar? c) What is the induced current in the bar when the terminal speed has been reached? d) After the terminal speed has been reached, at what rate id electrical energy being converted to thermal energy in the resistance of the bar? e) After the teminal speed has be... click for more

Inductance of a short coil

Have the inductance of the long coil which is L=( Meu (not)* N^2 * A ) / (D) A = Area , D = Length , N = number of turns in the coil Need to prove that for a short coil the inductance (L) is the following: L =[( Meu (not)* N^2 * A ) / (D)] * [ [{(D^2 - a^2)^(1/2)} - a ] / (D)] ] a = radius of the coil A = 3.14 a^2

describe how radio waves are converted to audible sound

Please explain how radio waves are converted to audible sound waves. A diagram would be helpful in the explanation.