Question

find the value of the voltage across the 4 ohm resistor.

pls help me answer this ​

Answer 1

Answer:

Voltage across the 4Ohm Resistor v = 432/35 V = 12.343 V

Explanation:

First convert the load on the right to a resistor.

If it draws 60W at 12v then P = V²/R ⇒ 60=12²/R ⇒ R = 2.4 Ohm

Then combine with the 4 Ohm resistor in parallel. The voltage across this new resistor will still be the same as the voltage across the 4Ohm.

For parallel resistors the resitance is Product over sum.

R = R1 * R2 / (R1 + R2) = 4 * 2.4 / (4 + 2.4) = 1.5 Ohm

Now the current flowing through this new resistor must be the sum of the currents flowing through the other two. Let's call the voltage across the 1.5 Ohm Resistor v. Now we can set up some equations to equate the currents in terms of v. Using Ohms law I = V/R. The current through something is the voltage across it over its resistance.

Current across left cell + current across right cell = current through 1.5Ohm resistor.

(24-v)/1 + (12-v)/0.1 = (v-0)/1.5

24 - v + 120 - 10v = 2v / 3

144 - 11v = 2v / 3

432 - 33v = 2v

432 = 35v

v = 432/35 V = 12.343 V