Advertisements
Advertisements
प्रश्न
The circuit in figure shows two cells connected in opposition to each other. Cell E1 is of emf 6V and internal resistance 2Ω; the cell E2 is of emf 4V and internal resistance 8Ω. Find the potential difference between the points A and B.
Advertisements
उत्तर
In this problem, after finding the electric current flow in the circuit by using Kirchoff’s law or Ohm’s law, the potential difference across AB can be obtained.
Applying Ohm's law.
Equivalent emf of two cells = 6 – 4 = 2V and equivalent resistance = 2Ω + 8Ω = 10Ω, so the electric current is given by
`I = (6 - 4)/(2 + 8)` = 0.2 A
Taking loop in anti-clockwise direction, since E1 > E2
The direction of flow of current is always from high potential to low potential.
Therefore VB > VA.
⇒ VB – 4V – (0.2) × = VA
Therefore, VB – VA = 3.6V
Important point: Sign convention for the application of Kirchoff’s law: For the application of Kirchoff’s laws following sign convention are to be considered.
(i) The change in potential in traversing a resistance in the direction of current is – iR while in the opposite direction + iR.
(ii) The change in potential in traversing as emf source from negative to positive terminal is +E while in the opposite direction – E irrespective of the direction of current in the circuit.
APPEARS IN
संबंधित प्रश्न
State the two Kirchhoff’s rules used in electric networks. How are there rules justified?
Given n resistors each of resistance R, how will you combine them to get the (i) maximum (ii) minimum effective resistance? What is the ratio of the maximum to minimum resistance?
State Kirchhoff's rules and explain on what basis they are justified.
Determine the equivalent resistance of networks shown in Fig.
State Kirchhoff's rules for an electric network. Using Kirchhoff's rules, obtain the balance condition in terms of the resistances of four arms of Wheatstone bridge.
In the given circuit, assuming point A to be at zero potential, use Kirchhoff’s rules to determine the potential at point B.
Find the circuit in the three resistors shown in the figure.
Consider the circuit shown in the figure. Find (a) the current in the circuit (b) the potential drop across the 5 Ω resistor (c) the potential drop across the 10 Ω resistor (d) Answer the parts (a), (b) and (c) with reference to the figure.
In the circuit shown in the figure below, E1 and E2 are two cells having emfs 2 V and 3 V respectively, and negligible internal resistance. Applying Kirchhoff’s laws of electrical networks, find the values of currents l1 and I2.
Solve the following question.
Using Kirchhoff’s rules, calculate the current through the 40 Ω and 20 Ω resistors in the following circuit.
State Kirchhoff ’s voltage rule.
State the principle of potentiometer.
Obtain the condition for bridge balance in Wheatstone’s bridge.
Lightning is a very good example of a natural current. In typical lightning, there is 109 J energy transfer across the potential difference of 5 × 107 V during a time interval of 0.2 s. Using this information, estimate the following quantities:
- the total amount of charge transferred between cloud and ground
- the current in the lightning bolt
- the power delivered in 0.2 s.
A potentiometer wire has a length of 4 m and resistance of 20 Ω. It is connected in series with resistance of 2980 Ω and a cell of emf 4 V. Calculate the potential along the wire.
In a potentiometer arrangement, a cell of emf 1.25 V gives a balance point at 35 cm length of the wire. If the cell is replaced by another cell and the balance point shifts to 63 cm, what is the emf of the second cell?
Two cell of 1.25 V and 0.75 V are connected parallel. The effective voltage will be:-
Kirchhoff’s junction rule is a reflection of ______.
- conservation of current density vector.
- conservation of charge.
- the fact that the momentum with which a charged particle approaches a junction is unchanged (as a vector) as the charged particle leaves the junction.
- the fact that there is no accumulation of charges at a junction.
What is the advantage of using thick metallic strips to join wires in a potentiometer?
State the two Kirchhoff’s rules used in the analysis of electric circuits and explain them.
