In an experiment this circuit is set up. Three ammeters are used to record the currents in the three vertical branches (with
R_{1} ,
R_{2} , and
E) . The readings of the ammeters in the resistor branches (i.e. currents in
R_{1} and
R_{2} ) are 2 A and 3 A respectively.
Find the equation obtained by applying Kirchhoff’s loop rule in the loop involving
R_{1} and
R_{2} .
What will be the reading of the third ammeter (i.e. the branch with
E )? If
E were replaced by 3
E , how would this reading change?
If the original circuit is modified by adding another voltage source (as shown in the following circuit), find the readings of the three ammeters.
In this circuit, assume the currents through
R_{1} ,
R_{2} and
R_{3} are
I_{1} ,
I_{2} and
I_{3} respectively and all are flowing in the clockwise direction.
Find the equation obtained by applying Kirchhoff’s junction rule at point A.
Find the equations obtained by applying Kirchhoff’s loop rule in the upper and lower loops.
Assume
R_{1} =
R_{2} = 6 Ω,
R_{3} = 12 Ω,
r_{1} =
r_{2} = 0 Ω,
E_{1} = 6 V and
E_{2} = 4 V. Calculate
I_{1} ,
I_{2} and
I_{3} .
For the situation in which
E_{2} is replaced by a closed switch, repeat parts (a) and (b). Using the values for
R_{1} ,
R_{2} ,
R_{3} ,
r_{1} and
E_{1} from part (c) calculate the currents through the three resistors.
For the circuit in part (d) calculate the output power of the voltage source and across all the resistors. Examine if energy is conserved in the circuit.
A student implemented the circuit of part (d) in the lab and measured the current though one of the resistors as 0.19 A. According to the results calculated in part (d) identify the resistor(s). Justify any difference in measured and calculated value.
I
_{1} + I
_{3} = I
_{2}
E
_{1} - I
_{1} R
_{1} - I
_{2} R
_{2} - I
_{1} r
_{1} = 0;
-E
_{2} + I
_{1} R
_{1} - I
_{3} R
_{3} - I
_{3} r
_{2} = 0
I
_{1} = 8/15 A,
I
_{2} = 7/15 A and
I
_{3} =
- 1/15 A
I
_{1} = 2/5 A,
I
_{2} = 3/5 A and
I
_{3} = 1/5 A
P
_{E1} = 18/5 W and
P
_{R1} = 24/25 W,
P
_{R2} = 54/25 W,
P
_{R3} = 12/25 W. Yes,
P
_{E1} =
P
_{R1} +
P
_{R2} +
P
_{R3}
Kirchhoff’s rules can be used to analyze any circuit, simple or complex.
Kirchhoff’s first rule—the junction rule: The sum of all currents entering a junction must equal the sum of all currents leaving the junction.
Kirchhoff’s second rule—the loop rule: The algebraic sum of changes in potential around any closed circuit path (loop) must be zero.
The two rules are based, respectively, on the laws of conservation of charge and energy.
When calculating potential and current using Kirchhoff’s rules, a set of conventions must be followed for determining the correct signs of various terms.
The simpler series and parallel rules are special cases of Kirchhoff’s rules.
Conceptual questions
Can all of the currents going into the junction in
[link] be positive? Explain.
Apply the junction rule to junction b in
[link] . Is any new information gained by applying the junction rule at e? (In the figure, each emf is represented by script E.)
(a) What is the potential difference going from point a to point b in
[link] ? (b) What is the potential difference going from c to b? (c) From e to g? (d) From e to d?
Consider the circuit in
[link] , and suppose that the emfs are unknown and the currents are given to be
${I}_{1}=5\text{.}\text{00 A}$ ,
${I}_{2}=3\text{.0 A}$ , and
${I}_{3}=\mathrm{\u20132}\text{.}\text{00 A}$ . (a) Could you find the emfs? (b) What is wrong with the assumptions?
(a) No, you would get inconsistent equations to solve.
(b)
${I}_{1}\ne {I}_{2}+{I}_{3}$ . The assumed currents violate the junction rule.
power P = Work done per second W/ t. It means the more power, the stronger machine
Sphere
e.g. heart Uses 2 W per beat.
Rohit
A spherica, concave shaving mirror has a radius of curvature of 32 cm .what is the magnification of a persons face. when it is 12cm to the left of the vertex of the mirror
my name is Abu m.konnek
I am a student of a electrical engineer and I want you to help me
Abu
the magnification k = f/(f-d) with focus f = R/2 =16 cm; d =12 cm
k = 16/4 =4
Sphere
A weather vane is some sort of directional arrow parallel to the ground that may rotate freely in a horizontal plane. A typical weather vane has a large cross-sectional area perpendicular to the direction the arrow is pointing, like a “One Way” street sign. The purpose of the weather vane is to indicate the direction of the wind. As wind blows pa
the same behavior thru the prism out or in water bud abbot
Ju
If this will experimented with a hollow(vaccum) prism in water then what will be result ?
Anurag
What was the previous far point of a patient who had laser correction that reduced the power of her eye by 7.00 D, producing a normal distant vision power of 50.0 D for her?
What is the far point of a person whose eyes have a relaxed power of 50.5 D?
Jaydie
What is the far point of a person whose eyes have a relaxed power of 50.5 D?
Jaydie
A young woman with normal distant vision has a 10.0% ability to accommodate (that is, increase) the power of her eyes. What is the closest object she can see clearly?
Jaydie
29/20 ? maybes
Ju
In what ways does physics affect the society both positively or negatively
Propose a force standard different from the example of a stretched spring discussed in the text. Your standard must be capable of producing the same force repeatedly.