Question

1. Послідовно з'єднані 2 резистори опорами R1 = 10 ом та R 2 -20 ом. В схемі І=5А. На резистор якого опору необхідно замінити R 2, щоб I= 8А при незмінній напрузі.​ Даю 25 балов

Answer 1

Problem Analysis

We have a circuit with two resistors, R1 with a resistance of 10 ohms and R2 with a resistance of 20 ohms. The current in the circuit is 5A. We need to determine the resistance of the resistor, R2, that needs to be replaced in order to have a current of 8A while keeping the voltage constant.

Solution

To solve this problem, we can use Ohm's Law, which states that the current flowing through a conductor is directly proportional to the voltage across the conductor and inversely proportional to the resistance of the conductor.

According to Ohm's Law, the current (I) can be calculated using the formula:

I = V / R

Where I is the current, V is the voltage, and R is the resistance.

In this case, we want to keep the voltage constant and change the current. Since the voltage is constant, we can set up the following equation:

I1 = I2

Where I1 is the initial current (5A) and I2 is the desired current (8A).

Let's calculate the voltage using Ohm's Law for the initial current:

V1 = I1 * R1

Substituting the given values, we get:

V1 = 5A * 10Ω = 50V

Now, let's calculate the resistance needed to achieve the desired current:

V2 = I2 * R2

Substituting the given values and the calculated voltage, we get:

50V = 8A * R2

Simplifying the equation, we find:

R2 = 50V / 8A = 6.25Ω

Therefore, the resistance of the resistor, R2, that needs to be replaced is 6.25 ohms in order to have a current of 8A while keeping the voltage constant.

Conclusion

To achieve a current of 8A while keeping the voltage constant in the given circuit, the resistor with a resistance of 20 ohms needs to be replaced with a resistor with a resistance of 6.25 ohms.