how to solve equation and mark value on its graph?

Let's say r = 200 ohm, and c = 200 microF

I have the following equation

Vc = V*(1-exp(-t./(R*C)));

and I need to solve it to get the value of t when v = 8 volts.

[Image Analyst]

What is v? Or did you mean V (MATLAB is case sensitive) or Vc?

And what is V?

Is this homework:

How do I get help on homework questions on MATLAB Answers? - MATLAB Answers - MATLAB Central

If I guess V = 10, I get this:

R = 200 % ohm and 
C = 200 % microF
C = C * 1e-6 % Farads
V = 10;  % Volts  Guessing here!
% I have the following equation 
t = linspace(0, .6, 1000);
Vc = V * (1 - exp(-t ./ (R * C)))
plot(t, Vc, 'b-', 'lineWidth', 2);
grid on;
xlabel('t', 'FontSize', 20);
ylabel('Vc', 'FontSize', 20);
yline(8, 'Color', 'r', 'LineWidth', 2);
% and i need to solve it to get the vakue of t when v = 8 v 

[hassan elkholy]

thanks for your answer :)

i need to see the value of t at vc = 8 as an answer also , can you help me

Answer 1

[KSSV]

 syms Vc V t R C
eqn = Vc - V * (1 - exp(-t ./ (R * C)))==0 ;
s = solve(eqn,t)

s = 

The above is the formula from the equation to solve for t. Substitute your values and get the values of t.