LCR circuit and frequency equation

In summary, when analyzing your LCR circuit data, it's important to carefully consider your calculations and uncertainties, as well as the physical meaning of the equations and your data.
  • #1
Howlin
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0

Homework Statement


Im doing a lab experiment on LCR circuits and have gotten a graph of 1/capacatance against frequency^2. With my results I got the slope to be 0.89±0.01 and the intercept is 358708±43189


Homework Equations


the equation that was given was
frequency^2=(1/4*pi*L)[(1/C) - (R^2/2L)]
we then get
f^2 = 1/(4*pi*L*C) -R^2/(8*pi*L^2)

The Attempt at a Solution



since y =mx + c

the slope is
m=1/(4*pi*L) where m is 1/C
then c = -R^2/(8*pi*L^2)
we rearrrange the first equation to get L= 1/(4*pi*m) then when we know L we can get R
R^2 = -c*8*pi**l^2

When I put in my values for m for the first equation I get L = 2.85E-2 Henry
Then when to get R^2 I can as you can't the square of a negative number.

Would I get the positive of the R^2 value and then say the resistance is (plus/minus) 151 ohms?
Or can someone tell me what I am doing wrong
my lecturer does not know what is wrong so I kinda want to get it right
 
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  • #2
.

First, it's important to double check your calculations and make sure all of your units are consistent. For example, in your first equation, the units for m should be in units of 1/F (farads) and not Hz^2 (hertz squared). This may be causing some confusion in your calculations.

Next, it's important to consider the uncertainty in your slope and intercept values. The fact that your slope value has an uncertainty of 0.01 indicates that your data may not be very precise. This could be due to experimental error or limitations in your equipment. It's also possible that your data may not fit the theoretical equation very well, which could also contribute to the uncertainty.

In terms of finding the values for L and R, you can use your equations to calculate these values, but it's important to also consider the uncertainty in your calculations. For example, using your calculated value for m and its uncertainty, you can calculate a range of values for L, and similarly for R using your calculated value for c and its uncertainty. This will give you a range of possible values for L and R, rather than just a single value.

In terms of the sign of R, it's important to consider the physical meaning of the equation. In this case, R represents the resistance in the circuit, which cannot be negative. So when solving for R, you should take the positive value.

Overall, it's important to carefully consider your calculations and uncertainties, and to also take into account the physical meaning of the equations and your data. If you're still unsure, it may be helpful to consult with your instructor or a classmate for further clarification.
 

1. What is an LCR circuit?

An LCR circuit is a type of electrical circuit that contains an inductor (L), a capacitor (C), and a resistor (R). It is also known as a resonant or tuned circuit because it can store energy at a specific frequency, known as the resonant frequency.

2. What is the formula for calculating the resonant frequency of an LCR circuit?

The resonant frequency (f) of an LCR circuit can be calculated using the formula: f = 1/(2π√(LC)), where L is the inductance in henries and C is the capacitance in farads.

3. How does the frequency affect the behavior of an LCR circuit?

The frequency of an LCR circuit directly affects its impedance, or resistance to the flow of electricity. At the resonant frequency, the impedance is at its minimum value, allowing for a maximum flow of current. At frequencies above or below the resonant frequency, the impedance increases and the circuit behaves differently.

4. What is the use of an LCR circuit in practical applications?

LCR circuits have a variety of uses in practical applications, including in radio and television receivers, electronic filters, and signal amplifiers. They are also commonly used in power supplies and electronic equipment to regulate and stabilize voltage.

5. What factors can affect the resonant frequency of an LCR circuit?

The resonant frequency of an LCR circuit can be affected by several factors, including the values of the inductor and capacitor, the resistance of the circuit, and the surrounding environment. Changes in these factors can alter the resonant frequency and performance of the circuit.

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