Semiconductor resistor in series with a capacitor -- Energy gap

In summary, to find the resistance in this circuit, you will need to use Ohm's Law and the given equations for the voltage and current in the capacitor. The final equation for the resistance will involve the frequency, capacitance, and voltage in the circuit.
  • #1
Granger
168
7

Homework Statement


Consider a circuit that consists on a resistor of an intrinsic semiconductor R and a capacitor C in series. The voltage between the terminals of the circuit is U, which is an alternated sinusoidal voltage.
U1, which is the voltage in the capacitor as a phase difference of 30 degrees from the voltage U for a temperature of 300K and a phase difference of 9 degrees at 330 K
What is the energy gap in the

Homework Equations


I = jwC Uc

The Attempt at a Solution


I have no idea where to start.
I know that I have to relate my voltages but I have no idea how, since they just say they have a ohase difference.
I know that the fraction between the phasors of U and U1 must then be $$e^{j\pi/6}$$. But how do I relate this to the resistance?
This j however confuses me...

Then after I get my resistances I know how to proceed

By applying:
$$R/R'=e^{\frac{W_G(T'-T)}{2KTT'}}$$

And solving this equation I get W_G.

So yeah basically my problem is how to work the circuit to find the resistance.

Can someone give me a little help?
 
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  • #2


Hi there,

To find the resistance in this circuit, you will need to use Ohm's Law, which states that the current through a conductor is directly proportional to the voltage and inversely proportional to the resistance. In this case, the voltage across the resistor is U, and the current through the resistor is I. So we can write:

$$I=\frac{U}{R}$$

We can also use the equation given in the problem to relate the voltage across the capacitor, Uc, to the voltage across the resistor, U:

$$Uc=Ue^{j\pi/6}$$

Using this equation, we can substitute for Uc in the first equation:

$$I=\frac{Ue^{j\pi/6}}{R}$$

Now, we can use the given equation for the current through the capacitor, I=jwCUc, to solve for R:

$$I=\frac{jwCUc}{R}$$

Substituting for Uc, we get:

$$I=\frac{jwCUe^{j\pi/6}}{R}$$

Finally, we can solve for R:

$$R=\frac{jwCUe^{j\pi/6}}{I}$$

This should give you the resistance in terms of the other variables. Let me know if you have any other questions.
 

Related to Semiconductor resistor in series with a capacitor -- Energy gap

1. What is a semiconductor resistor?

A semiconductor resistor is a type of resistor that is made from a semiconductor material, such as silicon or germanium. It is used to control the flow of electric current in a circuit by providing resistance.

2. What is a capacitor?

A capacitor is an electronic component that stores electrical charge. It is made up of two conductive plates separated by an insulating material, and it is commonly used in electronic circuits to store and release energy.

3. How does a semiconductor resistor in series with a capacitor work?

When a semiconductor resistor is connected in series with a capacitor, it forms an RC circuit. The resistor controls the flow of current, while the capacitor stores and releases energy. Together, they can be used to filter AC signals or create a time delay in a circuit.

4. What is the energy gap in a semiconductor resistor?

The energy gap in a semiconductor resistor refers to the energy difference between the valence band and the conduction band. This energy gap determines the conductivity of the material and can be controlled by adding impurities to the semiconductor.

5. What are some common applications of a semiconductor resistor in series with a capacitor?

Some common applications of this combination include signal filtering, time delay circuits, and oscillators. They are also used in electronic devices such as radios, amplifiers, and power supplies.

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