Answer:
The voltage drop across the unknown resistor is 6 volts.
Explanation:
Given;
the current flowing in the series circuit, I = 1.5 A
number of batteries in the series circuit, = 3
voltage in each battery = 9V
total voltage in the circuit, 3 x 9V = 27 V
number of resistor in the circuit, = 4
R₁ = 3 ohms
R₂ = 6 ohms
R₃ = ?
R₄ = 5 ohms
Determine the total resistance in the circuit by applying Ohms law;
V = IR
R = V / I
R = 27 / 1.5
R = 18 ohms
Determine the unknown resistance;
R₁ + R₂ + R₃ + R₄ = 18 ohms
3 + 6 + R₃ + 5 = 18
R₃ = 18 - 14
R₃ = 4 ohms
The voltage drop across the unknown resistor (R₃ = 4 ohms);
V₃ = IR₃
V₃ = 1.5 x 4
V₃ = 6 volts.
Therefore, the voltage drop across the unknown resistor is 6 volts.
