ToughSTEM
ToughSTEM
A question answer community on a mission
to share Solutions for all STEM major Problems.
Cant find a problem on ToughSTEM?
0
in the figure, both S1 and S2 are initially open. S2 is then closed and left closed until a constant current is established. The S2 is closed just as S1 is opened, taking the battery out of the circuit. Assume that R=515? and L= 305.0 mH

PART A

What is the initial current in the resistor just after S2 is closed and S1 is opened

PART B

What is the time constant of the circuit

PART C

What is the current in the resistor after a large number of time constants have elapsed
Edit
Added Tue, 04 Aug '15
Community
1
When does S1 get closed? The problem, as of 12/24/15, states that S2 is closed, but S1 is initially open. Bill N Thu, 24 Dec '15
Comment
Solutions
0

If S1 is initially closed while S2 is open, the current will climb like an "inverse exponential" from zero to a steady state value of V/R = 0.485 A.

The time constant of an RL circuit is given by $L_equiv/R_equiv$. In this circuit, that is simply 0.305/515 = 0.000592 s or 0.592 ms.

Because there is no power source to replenish the energy in the circuit, the resistor will eventually transfer the electrical energy out and the current will drop, exponentially, to zero: $i(t)=i_o exp(-Lt/R)$.

Edit
Added Thu, 24 Dec '15
Comment
0
when S1 is closed, current i = V/R

i = 250/515

i = 0.485 Amps

-----------------------------------------

time constant T = L/R

T = 0.305/515

T = 0.592 msecs

----------------------------------------

after many long time constants I = 0.367 Io

I = 0.367 *0.458

I = 0.168 Amps
Edit
Added Tue, 04 Aug '15
Community
1
Is this a real answer or a placeholder? The current goes to zero after many time constants. Bill N Thu, 24 Dec '15
Comment
Close

Choose An Image
or
Get image from URL
GO
Close
Back
Close
What URL would you like to link?
GO
α
β
γ
δ
ϵ
ε
η
ϑ
λ
μ
π
ρ
σ
τ
φ
ψ
ω
Γ
Δ
Θ
Λ
Π
Σ
Φ
Ω
Copied to Clipboard

to interact with the community. (That's part of how we ensure only good content gets on ToughSTEM)
OR
OR
ToughSTEM is completely free, and its staying that way. Students pay way too much already.
Almost done!