Home
Class 12
PHYSICS
Calculate the current through each resis...

Calculate the current through each resistance in the given circuit. Also calculate the potential difference between the points a and b.
`E_1 = 6V, E_2 = 8V, E_3 =10V`,
`R_1 =5 Omega`,` R_2 =10 Omega, R_3 =4Omega`
Assume that all the cless have no internal resistance.

Text Solution

Verified by Experts

The process of solving a circuit involves three steps:
i. Assume unkonwns (x, y, ….) for currents in different
branches of the circuit. Use Kirchhoff's Current law at
the junctins so that the number of unknowns introduced
is minimum. Let x be the current through `R_1` and y be the
current through `R_3` as shown in Fig. 5.74. Kirchhoff's
current law at the junction a gives a current (x-y)
through `R_2`

ii. Selectas many loops as the number of unknows introduced
for currents. Apply Kirchhoff's voltage law throgh every
loop. Going anticlockwise through the loop containing
`R_1 and R_3`(starting from junction a), we get
`+xR_1 - E_1 + yR_3 + E_3 = 0`
or 5x +4y = -4 ....(i)

Going clockwise through the loop containing `R_2 and R_3` (starting from juction a), we get
`-R_2(x-y) -E_2 +yR_3 + E_3 =0`
or 5x - 7y =1 (ii)
Some currents may come out to be negative. This simply
means that their directions were incorrectly assumed. so the signs of the currents will given us the correct direction
of each current. Solving Eqs. (i) and (ii) we get
`x = (-24)/(55) and y =(-5)/(11)A`
`:. x-y = (1)/(55)A`
This signs indicate that the direction of x and y were
assumed incorrectly, while the direction of (x-y) was
correct. So
current `i_1 ("through "R_1) = (24)/(55)`A toward left
current `i_2("through " R_2) = (1)/(55)` A toward right
current `i_3 ("through "R_3) =(5)/(11)` A upward
The current directions are shown in the circuit diagram

iii. Potential difference between a and b
The potentia difference between any two points in a
circuit is calculated by adding the changes in potential
while going through any path form one point to the other
point. Hence, let us go from b to a through `R_3.`
`V_a - V_b = +yR_3 + E_3 = ((-5)/(11))xx4+ 10 =(90)/(11)v`
Promotional Banner

Topper's Solved these Questions

  • ELECTRIC CURRENT AND CIRCUIT

    CENGAGE PHYSICS|Exercise Solved Examples|12 Videos
  • ELECTRIC CURRENT AND CIRCUIT

    CENGAGE PHYSICS|Exercise Exercise 5.1|28 Videos
  • ELECTRIC CURRENT & CIRCUITS

    CENGAGE PHYSICS|Exercise Kirchhoff s law and simple circuits|15 Videos
  • ELECTRIC FLUX AND GAUSS LAW

    CENGAGE PHYSICS|Exercise MCQ s|38 Videos

Similar Questions

Explore conceptually related problems

In the network shown the potential difference between A and B is (R = r_(1) = r_(2) = r_(3) = 1 Omega, E_(1) = 3V, E_(2) = 2V, E_(3) = 1V )

Find the magnitude and direction of the current flowing through the resistance R in the circuit shown in Fig. if the emf's of the sources are equal to E_(1) = 1.5 V and E_(2) = 3.7 V and the resistances are equal to R_(1) = 10 Omega, R_(2) = 20 Omega , R = 5.0 Omega . The internal resistances of the sources are neglible.

In the network shown the potential difference between A and B is R(=r_(1)=r_(2)=r_(3)=1Omega,E_(1)=3V,E_(2)=2V,E_(3)=1V)

In the circuit shown, E_(1)= 7 V, E_(2) = 7 V, R_(1) = R_(2) = 1Omega and R_(3) = 3 Omega respectively. The current through the resistance R_(3)

In the following circuit , E_1 = 4V, R_1 = 2 Omega, E_2 = 6 V, R_2 = 2Oemga, and R_3 = 4Omega. Find the currents i_1 and i_2

For the circuit shown, with R_1=1.0 Omega,R_2=2.0Omega,E_1=2V and E_2=E_3=4V the potential difference between the points ‘a’ and ‘b’ is __________(in V)

The emf of a cell is epsilon and its internal resistance is r. its termnals are cannected to a resistance R. The potential difference between the terminals is 1.6V for R = 4 Omega, and 1.8 V for R = 9 Omega. Then,

Determine the voltage drop across the resistor R_1 in the circuit given below with E = 65V, R_1 = 50 OmegaR_2 = 100 Omega, R_3 = 100 Omega, and R_4 300 Omega.