Calculate Power Absorbed by Each Element in Circuit

In summary, the circuit shown in the image requires determining the power absorbed by each element. The current through I(s) is -3A, indicating a 3A flow in the opposite direction into R(L). Therefore, the voltage across R(L) is V[R(L)]= 66V and the power absorbed is P[R(L)]= 198W. The total resistance around the circuit is 22 ohms, so the current through V(S) is I = 4/22 A and the power absorbed is P(S) = 8/11 W. The voltage through I(S) is V = -66V, resulting in a power absorbed of P[I(S)] = 198W. It is expected that the
  • #1
steven10137
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0

Homework Statement


For the following circuit, determine the power absorbed by each element
http://img401.imageshack.us/img401/840/pow2bl5.th.gif [Broken]

2. The attempt at a solution

This sign convention stuff is realllly confusing me.
Can someone give me some direction here?

The current through I(s) is -3A, this implies that there is 3A flowing in the opposite direction yeah? Hence there is 3A flowing into R(L).

The voltage across R(L) must then be: V[R(L)]= IR = 3 x 22 = 66V
Hence the power absorbed by R(L) is: P[R(L)]= VI = 66 x 3 = 198W


Here is where I start to get confused.
The total resistance around the circuit must be 22 ohms right?

The current through V(S) must then be I = V/R = 4/22 A
P(S) = VI = 4 x (4/22) = 8/11 W

The voltage through I(S) => V = IR = -3 x 22 = -66V
Hence the power absorbed by I(S) is: P[I(S)] = VI = -66 x -3 = 198W

Now I was under the impression that the Power generated must = Power abosrbed.
That doesn't work here ...

I'm not sure how much of this is right, but any help would be greatly appreciated.
Cheers
 
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  • #2
anyone?
 
  • #3


I would advise you to first review the basic concepts of circuits, including Ohm's Law and power calculations. It is important to understand the sign conventions and how to apply them correctly in circuit analysis.

In this circuit, it is important to note that the power generated by the voltage source is equal to the power absorbed by the resistors and the current source. This is due to the conservation of energy principle.

To calculate the power absorbed by each element, you can use the formula P = V*I, where V is the voltage across the element and I is the current flowing through it. The voltage across a resistor can be calculated using Ohm's Law, V = I*R.

For the resistor R(L), the current flowing through it is 3A and the voltage across it is 66V. Therefore, the power absorbed by R(L) is 198W.

For the resistor R(S), the current flowing through it is 4/22 A and the voltage across it is 4V. Therefore, the power absorbed by R(S) is approximately 0.73W.

For the current source I(S), the current flowing through it is -3A and the voltage across it is -66V. Therefore, the power absorbed by I(S) is also 198W.

Overall, the total power generated by the voltage source is 4V * 4/22 A = 0.73W. This is equal to the total power absorbed by all the elements in the circuit, which is 198W + 0.73W + 198W = 397.73W. This shows that the conservation of energy principle is satisfied in this circuit.

I would also recommend practicing more examples and problems to strengthen your understanding of circuit analysis and power calculations. Good luck!
 

1. How can I calculate the power absorbed by each element in a circuit?

To calculate the power absorbed by each element in a circuit, you will need to use the formula P = IV, where P is power in watts, I is current in amperes, and V is voltage in volts. You will need to calculate the current and voltage at each element and then use the formula to determine the power absorbed.

2. Do I need to take into account the direction of current flow when calculating power absorbed?

Yes, the direction of current flow is important to consider when calculating power absorbed. This is because the power absorbed by an element will depend on the direction of current flow and the polarity of the element. Make sure to use the correct signs for current and voltage when using the formula P = IV.

3. How do I determine the current and voltage at each element in a circuit?

To determine the current and voltage at each element in a circuit, you will need to use Ohm's Law (V = IR) and Kirchhoff's Voltage Law (KVL). Ohm's Law can be used to calculate the voltage across each element, while KVL can be used to determine the voltage drops across multiple elements in a loop. Once you have the voltage, you can use it to calculate the current at each element.

4. Is there a specific unit for power absorbed?

Yes, the unit for power absorbed is watts (W). This unit is a combination of the units for current (amperes) and voltage (volts). When using the formula P = IV to calculate power absorbed, make sure to use consistent units for current and voltage to get the correct result in watts.

5. Can I use the power absorbed by each element to determine the total power in a circuit?

Yes, you can use the power absorbed by each element to determine the total power in a circuit. Simply add up the power absorbed by each individual element to get the total power. Keep in mind that power is a scalar quantity, so you do not need to consider the direction of current flow when adding up the power absorbed by each element.

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