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Solution: Now that the equivalent resistance for R 2 and R 3 has been calculated, the circuit can be redrawn as a series circuit as shown in . We will be working backwards on this problem, using the current to find the resistance. There's absolutely no difference. The Thévenin equivalent internal resistance R T is the total resistance between A and B after shorting 1 0 obj %PDF-1.5 And if the question was asking the equivalent resistance between terminal b and a but not a and b, would it be just the equivalent resistance of 60 and 40 ohms resistances?

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How will you connect three resistors of 2 ohm, 3 ohm and 5 ohm respectively so as to obtain a resultant resistance of 2.5 ohm?

Solutions to the problems in Circuit Theory 1.

The equivalent resistance of this circuit (total resistance) can now be calculated. <>>> Four such combinations are connected in series. 2. endobj Figure 4(B).

2 0 obj Draw the diagram to show the arrangement. Practice: Finding equivalent resistance. ² we can further eliminate answers. endobj stream • Find equivalent resistor in new circuit • Solution: Original method: short terminals A and B as shown in the picture.

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What is the total resistance? Problem 60. We know the voltage and desired current, so we can calculate the total necessary resistance: Then we can calculate the equivalent resistance of the two resistors that are in parallel (R2 and our unknown): In which circuit would the bulbs be brighter? Given: Solution: The original circuit can be redrawn with a single resistor that represents the equivalent What is the equivalent resistance of this combination in terms of the original resistance R?

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Practice: Identifying types of resistor combinations. Ten identical bulbs are connected in a parallel circuit to an identical power supply line. 1.

R 3 R 4 R 5 R 2 R 1 + – V t i t However, this seems a bit pointless, because ﬁnding equivalent resistance using a test generator was as much work as ﬁnding the source current directly.

An electric bulb is rated as 10 W, 220 V. How many of these bulbs can be connected in parallel across the two wires of a 220 V supply line if the maximum current which can be drawn is 5 A. These five pieces of wire are then connected in parallel. Four resistances of 16 ohms each are connected in parallel. Problem 72. A wire of resistance R is cut into five equal pieces.

And we know that R 1 and R 2 are in parallel, so their equivalent resistance has to be less than 7 Ω (because for resistors in parallel, the equivalent resistance is always less than the branch with the smallest resistance). Find the equivalent resistance between points A and B. Which circuit would have the highest voltage across each bulb? 3 0 obj Solving a circuit with series and parallel resistors. Problem 71. Which circuit would have less current in it? We know that R 3 and R 5 are similarly in series with a resistance of 14 Ω. This is the currently selected item. 4 0 obj In which circuit, if one bulb blows out, all others will stop glowing? %���� e cient methods for calculating the equivalent resistance between nodes of highly symmetric networks. What is the equivalent resistance between points A and B. In fact, it took one extra step to ﬁnd the equivalent resistance.

Solution . Choosing two points establishes the resistance path for a passive circuit (no sources).

Then the equivalent resistance is R eq = 10 V / 5.02 mA = 1.99 kΩ. endstream endobj 2032 0 obj <. The order of the names means nothing. Solution . <> What possible values of resultant resistance can one get by combining two resistances, one of value 2 ohm and the other 6 ohm? Find the current I going through A to B. R th can be found by V/I,where V is the voltage we get from last problem.

Find the equivalent resistance between points A and B. Parallel resistors (part 3) Identifying types of resistor combinations. be 5.02 mA.

Draw the diagram to show the arrangement.