Solve Circuit Help: Find Io as Function of Frequency

  • Thread starter Thread starter stunner5000pt
  • Start date Start date
  • Tags Tags
    Circuit
AI Thread Summary
To find the initial current Io in a series circuit consisting of a battery, capacitor, inductor, and resistor, the impedance Z must be calculated. The impedance is expressed as Z = R + 1/(jωC) + jωL, where j is the imaginary unit and ω is the angular frequency. The initial current can then be derived using the formula Io = V0/Z, where V0 is the initial voltage from the battery. By substituting the impedance into this equation, Io can be expressed as a function of frequency. This approach utilizes Ohm's Law and the properties of complex numbers to simplify the expression for Io.
stunner5000pt
Messages
1,443
Reaction score
4
Circuit help! Please!

A battery is connecteed to a capacitor and the capacitor(C) is connected to an inductor(L) which si connected to a resistor (R) and the resistor is connected back to the battery ALL IN SERIES. A voltmeter is connected across the terminal of the resistor

Using I_{0} = \frac{V_{0}}{Z}
derive an expression for Io through the above described circuit as a function of frequency

Here anything with the subscript o means that it is the initial state.

I am not sure how they go about solving this but i know that the resonant frequency is given by

f = \frac{1}{2 \pi \sqrt{LC}}

but i am not sure on how to proceed is there some formula i don't know or am i missing??
 
Physics news on Phys.org
It looks like you know what the voltage across the circuit is, right? (from the battery). Then all you have to do to get Io is calculate the impedance Z (analogous to resistance) for the whole circuit. There are simple closed expressions for the impedance of various circuit elements that I trust you have or can easily find (or even derive, with a bit of complex calculus).
 


To solve this circuit and find Io as a function of frequency, we can use Ohm's Law and the impedance formula.

First, let's label the components in the circuit:

- V0: initial voltage of the battery
- C: capacitance of the capacitor
- L: inductance of the inductor
- R: resistance of the resistor

Using Ohm's Law, we know that V = IR, where V is the voltage across the resistor, I is the current flowing through it, and R is the resistance. Therefore, we can express I as:

I = \frac{V}{R}

Next, we need to find the impedance of the circuit, which is the total opposition to the flow of current. In a series circuit, the impedance is the sum of the individual impedances. In this case, the impedance is given by:

Z = R + \frac{1}{j\omega C} + j\omega L

where j is the imaginary unit and ω is the angular frequency.

Now, we can use the formula given in the question, I0 = \frac{V0}{Z}, to find Io as a function of frequency. Substituting the impedance formula into this equation, we get:

I_{0} = \frac{V_{0}}{R + \frac{1}{j\omega C} + j\omega L}

To simplify this expression, we can multiply the numerator and denominator by the complex conjugate of the denominator, which is R - \frac{1}{j\omega C} - j\omega L. This gives us:

I_{0} = \frac{V_{0}(R - \frac{1}{j\omega C} - j\omega L)}{(R + \frac{1}{j\omega C} + j\omega L)(R - \frac{1}{j\omega C} - j\omega L)}

Simplifying further, we get:

I_{0} = \frac{V_{0}(R - \frac{1}{j\omega C} - j\omega L)}{R^{2} + \frac{1}{\omega^{2}C^{2}} + j\omega L(R - \frac{1}{j\omega C} - j\omega L)}

Using the fact that j^{2} = -1, we can rewrite this as:

I_{
 
Thread 'Variable mass system : water sprayed into a moving container'
Starting with the mass considerations #m(t)# is mass of water #M_{c}# mass of container and #M(t)# mass of total system $$M(t) = M_{C} + m(t)$$ $$\Rightarrow \frac{dM(t)}{dt} = \frac{dm(t)}{dt}$$ $$P_i = Mv + u \, dm$$ $$P_f = (M + dm)(v + dv)$$ $$\Delta P = M \, dv + (v - u) \, dm$$ $$F = \frac{dP}{dt} = M \frac{dv}{dt} + (v - u) \frac{dm}{dt}$$ $$F = u \frac{dm}{dt} = \rho A u^2$$ from conservation of momentum , the cannon recoils with the same force which it applies. $$\quad \frac{dm}{dt}...
Back
Top