Understanding Capacitor Charging Time

[pat666]

Homework Statement

Please see the attachment
ok I am really not very good with this stuff at the moment. From reading the text I have gotten somewhere but have obviously screwed it up. ln -.3 doesn't exist obviously. Please help me with this. thanks

Homework Equations

The Attempt at a Solution

attempt can be seen in the same attachment as question. again I really need help with this..

 

[rock.freak667]

You have on the left side near to the end

0.7-1 = -e ^t

0.7-1 is -0.3

so you will end up with something like -0.3=-e^t. The -1s cancel.

 

[pat666]

oh ok thanks - is this the right procedure?

 

[rock.freak667]

Yes it should be.

 

[pat666]

thanks - do you know what's going on with my other problem that we had different answers to?