A voltage of 3 V is applied to a resistor with a resistance of 150 Ohms and a rheostat connected in series

| April 11, 2021 | education

A voltage of 3 V is applied to a resistor with a resistance of 150 Ohms and a rheostat connected in series to it, a determinant of the resistance value of the working part of the rheostat if the voltage across the resistor turned out to be 1 V

1. When connected in series, U = U1 + U2, where U is the voltage applied to the resistor and rheostat, U1 is the voltage across the resistor, U2 is the voltage across the rheostat.
Let’s find the voltage on the rheostat:
U2 = U-U1 = 3V-1V = 2V
2. When the elements are connected in series, the same current I, I = I1 = I2 passes through them.
3. Find the current flowing through the resistor, according to Ohm’s law:
I = U / R = U1 / R1 = U2 / R2, where R1 is the resistance of the resistor, R2 is the resistance of the rheostat, we substitute the numerical values, we get:
I = 1/150 = 0.0067A
4. Knowing the current in the circuit, we find the resistance of the rheostat:
R2 = U2 / I = 2 / 0.0067 = 300 Ohm

Answer: the resistance of the working part of the rheostat is 300 ohms.



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