I don't know how to figure out the value of this voltage formula: Vs= 10sin(2xpiexf)t There is a forward bias diode in the circuit followed by the one resistance in the circuit is 100k ohms. The frequency is 100hz, Can someone help?
It sounds like you're talking about a half wave rectifier with a 100k resistor hooked up as a load. The diode will be reverse biased on the negative swing of the sine wave so the voltage across the resistor will be 0 since the diode will stop current flow. When the input voltage is between 0.7V (Forward Diode Voltage assumption) and the maximum of 10V, the voltage across the resistor will be the source - 0.7V.
In your first post, you stated that Vs = 10sin(2pift) What is the maximum possible value for a sine? http://en.wikipedia.org/wiki/Sine
Remember: On the positive half-sine of the input, the output voltage is equal to the input. On the negative, the output is zero.