Posted by abdul rahman on .
A circuit consists of a self inductor of L=0.003 H in series with a resistor R1=5 Ohm. Parallel to these is a resistor R2=10 Ohm. A battery of V0=9 volt is driving the circuit.
Current has been running for 10 minutes.
(a) How much energy (in Joules) is now stored in the selfinductor.
(b) How much power (in Watt) is then generated by the battery into the circuit? (ignore internal resistance of the battery).
The connection to the battery is now broken (so that the battery is not connected to the circuit anymore).
(c) How long will it take (in seconds) for the current through R1 to be reduced by 50%?
(d) How long does it take (in seconds) till the energy stored in the selfinductor has been reduced by 50%?
(e) How long will it take (in seconds) for the current in R2 to be reduced by 50% (compared to the highest value right after the battery is disconnected)?

Physics 
abdul rahman,
plz help.....!

Physics 
s,
I can tell you a) & b)
a) Assuming after 10 min I=Imax then
I1=V/R1 and so the energy is 1/2*L*I1
b) I=V/Req (Req=(R1*R2)/(R1+R2)) So P=I*V 
Physics 
abdul rahman,
Thnx :) a) n b) are correct ! plz some one for c), d) n e) parts ???

Physics 
s,
For c) & e):For broken connection of V then Req is R1+R2 so the equation is :
Imax/2=Imax*e^((Req/L)*t) and Imax is the Imax from before the connection with the V was broken so Imax=V/R where R=(R1*R2)/(R1+R2) 
Physics 
s,
I still can't get the solution for d if i manage to get it i'll post it

Physics 
abdul rahman,
can u plz tell the answers in numerals for time in parts c) n e). I am unable to solve it correctly !

Physics 
s,
0.0001386 both. Spent a little time and put the equation in Wolfram alpha it's online calculator and it's very helpfull in general

Physics 
abdul rahman,
thnx c n e are correct !

Physics 
abdul rahman,
plz lemme knw the b) part when u are able to figure out !

Physics 
Anonymous,
d)since you have find a) then first you should find what the current is for the half energy 0.00486/2=0.00243 so 0.00243=1/2*0.003*I^2 so I=1.27279.the max current in the self inductor was i=9/5=1.8A so the equation is 1.27279=1.8*e^((15/0.003)*t)(R=(5+10)Ù because now the connection with v is broken)so t=0.0000693135

Physics 
FLu,
Can somebody help with Problem: Displacement Current please?
I thought the formula is:
(1.25663706*10^6*0.04*0.2*0.0705)/(2*pi*0.05^2)
However, I am not getting the correctr answer. 
Physics 
Anonymous,
FLu the formoula is (ì0*I)/(2*pi*r) and ì0=4*pi*10^7

Physics 
FLu,
Thanks Anonymous!
Do you have by any chance the answer for Problem:
Opening a Switch on an RL Circuit
b) and c)
I could figure out a)V_0/R_1
the other one seems more complicated.
Can you help please? 
Physics 
Anonymous,
FLu b) is the equation
I0*e^(((R1+R2)/L)*t) I had no luck with the others 
Physics 
FLu,
Many thanks Anonymous!
I got d) 100
Opening Switch on an RL Circuit:
b) seems in a way easier as most of the letters are not accepted only R1, R2 and V0.
Did somebody managed it yet? 
Physics 
dd,
a and d please

Physics 
FLu,
dd, I have provided a and b already just have a look above.
Anyone for c) please? 
Physics 
My,
Did somebody found c) yet please!?

Physics 
FLu,
Sorry meant a and d. b) was provided by Anonymous.
If anybody knows c), thanks in advance! 
Physics 
Ur,
Yes, please answer c) please!

Physics 
Lora,
c) please!

Physics 
Gema,
c) Anyone?

Physics 
FLu,
Anyone for c) guys please?

Physics 
My,
Was someone successful with c)?

Physics 
Supraconductor,
for C)... divide the b) by 2

Physics 
Anony,
PLEASE NUMERICAL ANSWERS FOR A) AND B)

Physics 
FLu,
Thanks Supraconductor.
I could not figure it out. Is it this:
V_0*e^(R_1+R_2)
Thanks in advance! 
Physics 
My,
Having problems with c) is well, was somebody able to come up with the expression?

Physics 
Haet,
Expression for c) please?

Physics 
Ula,
I tried it out now with the hint of Supraconductor but could not figured out. Did somebody manage it please?

Physics 
Terry,
c) please anyone!

Physics 
Ur,
Please c)?

Physics 
hmmmm,
c)0.0001386

Physics 
Ur,
Thanks hmmmm, I meant Problem:
Opening a Switch on an RL Circuit
Do you have c)? 
Physics 
FLu,
Anyone for Problem:
Opening a Switch on an RL Circuit: c)?
Thanks. 
Physics 
Anonymous,
Finally c)(V_0*(R_1+R_2))/R_1

Physics 
Anonymous,
(Part c for RL circuit)

Physics 
FLu,
Great many thanks Anonymous!

Physics 
P,
Please tell RL Circuit I2 I3 for b and c
ASAP