Question

Calculate the voltage at points A, B, and C, in the following circuit. Find the power dissipated by each resistor. 6 V Calculate the total current I flowing through the following circuit segment. Then, find the voltage drop across each resistor. -18 V 12 kΩ 12 k

Answer 1

(a)

Power dissipated across 10 k$\dpi{80} \Omega$ resistor,

P₁₀ = I²R = (0.6*10^-3)²*10 * 10³ = 0.36 * 10^-2 W

      = 3.6 *10^-3 W

Power dissipated across 1 k$\dpi{80} \Omega$ resistor,

P₁ = I²R = (3*10^-3)²*1 * 10³ = 9 * 10^-3 W

      = 9 *10^-3 W

(b)

Now,

From figure 3 of the circuit,

Current across 4$\dpi{80} \Omega$ resistor , i₁ = (5 / (5 + 4) ) * 5.4

                                                 = 5/9 * 5.4 = 3 mA

Current across 5$\dpi{80} \Omega$ resistor , i₂ = 2.4 mA

Now,

figure 2 of the circuit we can see, Current is same in 4k$\dpi{80} \Omega$ and 1 k$\dpi{80} \Omega$ resistors as they are in series. i.e 2.4 mA

Now,

In figure 1 of the circuit we can see, 4k$\dpi{80} \Omega$ resistor is made of three 12 k$\dpi{80} \Omega$ resistors connected in parallel.

Thus, current will be equally divided into the 12 k$\dpi{80} \Omega$ resistors.

=> i₃ = 2.4 / 3 = 0.8 mA

Thus,

Current across all the 12 k$\dpi{80} \Omega$ resistors is 0.8 mA

Current across 1 k$\dpi{80} \Omega$ resistors is 2.4 mA

Current across the 4 k$\dpi{80} \Omega$ resistors is 3 mA