Consider the network of four resistors shown in the diagram, where R 1 = 2.00 ?
ID: 1453105 • Letter: C
Question
Consider the network of four resistors shown in the diagram, where R1 = 2.00 ? , R2 = 5.00 ? , R3 = 1.00 ? , and R4 = 7.00 ? . The resistors are connected to a constant voltage of magnitude V.
(figure 1)
(figure 2)
Part A: Find the equivalent resistance RA of the resistor network
Part B: Two resistors of resistance R5 = 3.00 ? and R6 = 3.00 ? are added to the network, and an additional resistor of resistance R7 = 3.00 ? is connected by a switch, as shown in the diagram..(Figure 2) Find the equivalent resistance RB of the new resistor network when the switch is open.
Part C: Find the equivalent resistance RC of the resistor network described in Part B when the switch is closed.
Explanation / Answer
part a )
R1 and R2 in parallel and their equivqlen in series with R3 and R4
Req = R12 + R3 + R4
R12 = R1*R2 /R1+R2
Req = 9.4286 ohm
part b )
switch is open
so no current in R7
R1 and R6 in series and in parallel with R2
now their combination in series with R3 , R4 , R5
Req = R16 = R1 + R6
Req =[ (R1+R6)*R2 / (R1 + R2 + R6) ] + R3 + R4 + R5
Req = 13.5 ohm
part c )
now switch is closed
R4 and R7 in parallel
Req = (R16*R2 / R16 + R2 )+ R3 + R5 + (R4*R7/R4+R7)
Req = 8.6 ohm