Maple TA Quiz 20-1

Question 1: (Value in microF)*(Value in kiloOhm)*(10^-3)

Answer is negative.

Question 4: (Value in V)/(e^-((Value in ms*10^-3)/(Value in kiliOhm*Value in nF*10^-6)))

Answer is negative.

Any ideas on q2 and q3?

I cant figure out question 2 and 3 either can someone help plz?

Question 2: ((Value in kV*10^3)*(-((Value in s)/(Value in mF*Value in kOhm))))/(Value in kOhm*10^3)

Correct answer should be around 0.05.

Answer is negative.

Question 3: ln(1-(% provided/100))*(Value in microseconds)*10^-6

Answer is positive.

Sorry about the wait for these two. I was a bit tired the other day and simply had a bit of trouble with these (2,3) so I left them for today.

Sry helping, but #2 did not work for me.

I am having problems with this question, i used this equation provided above: ((Value in kV*10^3)*(-((Value in s)/(Value in mF*Value in kOhm))))/(Value in kOhm*10^3) and i am still not getting it right...

What is the discharging current in an RC circuit with a 0.2589 resistor and an initial voltage of 1.645 kV across a 50 mF capacitor after 27.49 s from the begin of the discharge (see sheet 8,8',9) ? Indicate with a negative (positive) sign whether the charging and discharging current have (do not have) the same functional dependence on time.

this is what i did:

((1.645*10^-3)*(-((27.49)/(50*.2589))))/(.2589*10^-3)

I cant figure out 2 either and I am following the method provided above anyone know how solve this question?

Check your signs. You have to -3's where it should be positive.

i changed my signs and still no good

hi helping. #2 is not working for me either. Could you take a shot at solving my problem for #2? I keep getting -20.96 as my answer when i do it the way you showed above but its incorrect when i put it in maple. i'd really appreciate it if you could help. thanks!

What is the discharging current in an RC circuit with a 0.1791 resistor and an initial voltage of 1.24 kV across a 50 mF capacitor after 27.11 s from the begin of the discharge (see sheet 8,8',9) ? Indicate with a negative (positive) sign whether the charging and discharging current have (do not have) the same functional dependence on time.

My mistake. I believe I left out the e^ before the - sign once you open the parentheses.

followed the method above for #2 n i still don't get it >< thanks if anyone can help!

The method above should work if done properly, however, your answer will not necessarily be around 0.05. Mine was actually 0.75.

((Value in kV*10^3)*(e^(-((Value in s)/(Value in mF*Value in kOhm)))/(Value in kOhm*10^3))

hope it helps!

use the equation Vc=Vo*e^(-t/RC)
remember e is actually one of the functions on the graphing calculator such that ln(e^x) will give you x
once you solved for Vc then use the equation Vc=Ic*R
remember Vc is the voltage discharge which is what you are solving for and Vo is just the initial voltage and Ic is just the current discharged from Vc

i still couldnt get #3 with the equation provided, my answer came out to be negative. helppp

use equation 20.5'. This gives you voltage...then divide by the resistance they give you to get the current. FORMULA: V(given)*e^(-t/RC)--> then divide by R

the power of e is negative. So when you do ln and the e comes off....you have -. Plus, ln(1-%/100) is negative. Multiply the 2 and you get positive.

anyone understand 4?

Don't be bothered with the value of 0.05 or whatever.

I got 3.04 as my value and got it right.