Question

need help with number 3

20 Q 2. Given the figure on the right, show that the 20power dissipated in one of the 10-2 C 2 2 15Q resistors is about 6 Watts 3. If e 9.0 V in the figure on the left, then show that the current in the 15-2 resistor is 0.20 A. www

Answer 1

>> Question 3 > Drawing the circuit diagram, Rio 2012 5730 32=R3 Rz. Tisa &= 9.ov (given) > Noming the sesi ters os R1, R2 x R3 s current through them as O į, is is respectively (as shown) > The obove problem can also be selved by Kerchoff's laws (very easily ) But we would be solving the problem using basics of electricity > concepts to be used 1 in some combination the cutrent Ocross the resistors o is equai x in parallel the voltage across them equas Chms lace says VERI V Voltage is current R= resistance. As we know that R2 R3 are connected in parallel So, the equivalent resistance of them would be R23. Calculating is too to take ! Rez= 10 ] Ri=202 drowing the reduced circuit. Ra3 = 10.1 E=407

Now, the equivalent resistance of the arcuit would be Ri (series) Rg3 So, Equivalent Resistance = Req = Ri+ R23 = 20+10 = 301 d Req=300 L1 E-9.0V Uy cuit > So, applying Ohm's law to the equivalent dis A &=-(Req.). > 4 %0A! current is also flowing through R23 = 101 R2=152 > Now exploring Ra3 =lon R3="302 Tove Voltage across R23 AV2 = Voltage across R2 OV = Voltage " B3 since, R2 R3 are in parallel, so, DVp = ove (Equal voltage) also loves AV = V23 Equivalent circuit for R2 R3

> Now, applying Ohm's law across R23 Vega (Ras les = (10)% = 3V Hence, ovo = OV2= DV23 = 3V across Ro= 151 > Again applying onm's law SV (R2) = V2= 3V current: la so, o Vez Rz iz = id= ! Cza 0.244 I Hence, proved in Rz= 152 resistor that the current 12 = 0.20 A