- #1

jaus tail

- 615

- 48

## Homework Statement

The time for which the diode conducts is

## Homework Equations

Using integration and differentiation Vc = 1 / C integral (current)(dt)

## The Attempt at a Solution

Vs = -Vc

Vm sin(wt) = -Vc = - (1/C) integral (Idt)

now differentiate both sides to get expression for I that is current.

Vm (coswt) * w = -(1/C) I

So I = Vm(costwt) * C * w (-1)

So now i draw current wave, and then how to proceed? How do you get an answer for this? Am i to find out when current goes negative?

There was a similar question for RL circuit that was

There was a similar question for RL circuit that was

__Vs = L di/dt__

so integrate to get expression for current.

Vs sin(wt) = L di/dt

Vs sin (wt) dt = L di

integrating

Vs cos (wt) (-1) / w + k = L * I

I = Vs cos (wt) (-1) /(wL) + k' where k' = k/L equation 1

to find value of K' take initial condition. At t = 0, I = 0

so 0 = Vs (1) (-1) / (wL) + k' from equation 1

K' = Vs/(wL) equation 2

so expression for current becomes from equation 1 and 2

I = Vs cos(wt) (-1) / (wL) + Vs / (wL) = Vs/ (wL) * (1 - cos (wt))

Drawing this we get I is always positive, so it conducts for 360 degrees when input goes 1 entire cycle.

360 degrees was right for RL circuit but for RC answer is not given as the book is old and the page is torn.

so integrate to get expression for current.

Vs sin(wt) = L di/dt

Vs sin (wt) dt = L di

integrating

Vs cos (wt) (-1) / w + k = L * I

I = Vs cos (wt) (-1) /(wL) + k' where k' = k/L equation 1

to find value of K' take initial condition. At t = 0, I = 0

so 0 = Vs (1) (-1) / (wL) + k' from equation 1

K' = Vs/(wL) equation 2

so expression for current becomes from equation 1 and 2

I = Vs cos(wt) (-1) / (wL) + Vs / (wL) = Vs/ (wL) * (1 - cos (wt))

Drawing this we get I is always positive, so it conducts for 360 degrees when input goes 1 entire cycle.

360 degrees was right for RL circuit but for RC answer is not given as the book is old and the page is torn.

i'm not sure what to do in case of given question of diode + C with charged as shown.

Expression is

I = Vm(costwt) * C * w (-1)

So what to now?