الفيزياء العامة الجزء الثاني#موقع الفيزياء.كوم

Lectures in General Physics
Q I
ζ
=
R
therefore,
R = R 1 + R 2 + R 3
This is the same result obtained in section 7.1.1
To find the potential difference between points a and b V ab (=V a -V b ) we use
the second Kirchhoff’s rule along a direction starting from point (b) and
finish at point (a) through the resistors. We get
V b + IR = V a
Where R is the equivalent resistance for R 1 , R 2 and R 3
V ab = V a - V b = + IR
The +ve sign for the answer means that V a > V b
Substitute for the current I using the equation
I
ζ
=
R
we get
V ab = ξ
This means that the potential difference between points a and b is equal to
the emf in the circuit (when the internal resistance of the battery is
neglected).
Example 8.5
In the circuit shown in figure 8.8 let ξ 1 and ξ 2 be 2v and 4v,
respectively; r 1 ,r 2 and R be 1Ω, 2Ω, and 5Ω, respectively. (a) What is
Dr. Hazem Falah Sakeek