Suppose you had a circuit with three resistors in series and you measured I=7.0 milliamps; V = 14.7 volts; V1= 3.5 volts and V2 = 1.4 volts. What would be the voltage across the third resistor? What would its resistance be?
the total = 14.7
so
3.5 + 1.4 + V3 = 14.7
R3 = V3/(7*10^-3)
To find the voltage across the third resistor and its resistance, we can use Ohm's Law and Kirchhoff's Voltage Law (KVL).
1. Use Ohm's Law (V = IR) to find the total resistance (R):
Since the three resistors are connected in series, we can add up their individual resistances:
R_total = R1 + R2 + R3
2. Use Ohm's Law again to find the current (I) flowing through the circuit:
I = V / R_total
3. Use KVL to find the voltage across the third resistor (V3):
KVL states that the sum of the voltage drops across each element in a closed loop is equal to the sum of the source voltages in that loop.
V = V1 + V2 + V3
Rearrange the equation to solve for V3:
V3 = V - V1 - V2
4. Finally, substitute the given values into the equations to find the voltage across the third resistor (V3) and its resistance.
Let's plug in the given values:
I = 7.0 milliamps = 7.0 * 10^(-3) A
V = 14.7 volts
V1 = 3.5 volts
V2 = 1.4 volts
Step 1:
To find the total resistance (R_total), we need the values of R1, R2, and R3. However, these values are not given in the question. So without the resistances, we cannot determine the values of V3 and R3.
To calculate V3 and R3, we need additional information.