What is the Resistance and Current in the Circuit?

In summary, the current in resistor R is 2A using KCL, the resistance R is 5 ohms, the unknown emf is 42V using KVL of the bottom loop, and the current in resistor R is 3.5A when the circuit is broken at point x. The simplified circuit is a loop with 28V, 5 ohms, and 3 ohms in series, resulting in a current of 3.5A. The equivalent resistance for the loop is 8 ohms.
  • #1
Chandasouk
165
0
n the circuit shown in the figure find (a) the current in resistor R, (b) the resistance R, (c) the unknown emf, (d) f the circuit is broken at point x , what is the current in resistor R?

YF-26-21.jpg


A) 2A using KCL
B)
C) 42V using KVL ofthe bottom loop
D)

For B, is the resistor 5 ohms? I'm not sure if I wrote my KVL correctly since the notation is different from my Electrical Engineering class but I wrote a KVL at the top loop, starting from the node to the left of the 28V voltage source, going clockwise so

-28-(-2A)R - 24V + 42V = 0

R = 5 ohms? I used -2A because I was going the opposite direction of the regular current.

That would mean for part D, the circuit simplifies to the loop of 28V-5 ohms-3ohms.

5 and 3 are in series so their equivalent resistance is 8. Then using V=IR, I is 28V/8 ohms
 
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  • #2
Yes, 5 ohm.
D: ok
 

FAQ: What is the Resistance and Current in the Circuit?

1. What is resistance and why is it important in a circuit?

Resistance is a measure of how much a material or component opposes the flow of electric current. It is important in a circuit because it determines the amount of current that can flow through the circuit and affects the overall performance of the circuit.

2. How is resistance calculated in a circuit?

Resistance is calculated using Ohm's Law, which states that resistance (R) is equal to the ratio of voltage (V) to current (I). This can be written as R = V/I, where R is measured in ohms (Ω), V is measured in volts (V), and I is measured in amps (A).

3. What factors affect the resistance in a circuit?

The resistance in a circuit is affected by the material of the components, the length and thickness of the wires, and the temperature of the circuit. Generally, materials with high resistivity and longer and thinner wires will have higher resistance, while materials with low resistivity and shorter and thicker wires will have lower resistance. Higher temperatures also increase resistance in most materials.

4. How do you measure resistance in a circuit?

Resistance can be measured using a multimeter, which is a device that measures voltage, current, and resistance. The multimeter is connected to the circuit and measures the voltage across the component and the current flowing through it. The resistance is then calculated using Ohm's Law.

5. How can you reduce resistance in a circuit?

To reduce resistance in a circuit, you can use materials with low resistivity, such as copper or silver, for the components and use shorter and thicker wires. You can also avoid sharp bends or kinks in the wires, as these can increase resistance. Additionally, keeping the circuit at a lower temperature can help reduce resistance.

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