Question

(i) State the two Kirchhoff’s laws. Explain briefly how these rules are justified.
(ii) The current is drawn from a cell of emf E and internal resistance r connected to the network of resistors each of resistance r as shown in the figure. Obtain the expression for (i) the current draw from the cell and (ii) the power consumed in the network.

Answer 1

Answer:

it stared

Explanation:

State the two Kirchhoff’s laws. Explain briefly how these rules are justified.

(ii) The current is drawn from a cell of emf E and internal resistance r connected to the network of resistors each of resistance r as shown in the figure. Obtain

Answer 2

Explanation:

junction law : at any Junction the sum of current entering is equal to current leavings

.

$\sum{( \triangle \: I) = 0}$

this law is accord with law of conservation

loop law : algebraic sum of change in potential around any closed loop is zero

$\sum{( \triangle\: i) = 0}$

this is accord with conservation of energy

please see the attachment then you will find that

1/Req= 1/r + 1/2r + 1/2r + 1/r

so Req= r/3

Now current value use the formula

E= I(R+r)

where E is emf

R is external resistance

r is internal resistance

I is current

so I =

$\frac{E}{R + r} = \frac{E}{ \frac{r}{3} + r} = \frac{3E}{4r}$

power p= I^2(r/3)=3E^2/4r