
The diagram above shows a circuit with the key k open. Calculate

(A) The resistance of the circuit when the key k is open.
(B) The current drawn from the cell when the key k is open.
(C) The resistance of the circuit when the key k is closed.
(D) The current drawn from the cell when the key k is closed.
Answer
154.2k+ views
Hint: When the key k is closed, the current passes through the entire circuit and through all three resistors. When the key k is open, the current passes through the resistor only.
Formula Used: The formulae used in the solution are given here.
If the resistors are linked in series, the series resistance is articulated as-
If the resistors are linked in parallel, the series resistance is articulated as-
By Ohm’s Law, we know that, where is the resistance, is the voltage across its ends and is the current.
.
Complete Step by Step Solution: Resistance is the measure of opposition applied by any object to the flow of electric current. A resistor is an electronic constituent that is used in the circuit with the purpose of offering that specific amount of resistance.
If the resistors are linked in series, the series resistance is articulated as-
If the resistors are linked in parallel, the series resistance is articulated as-
For the circuit given above, the resistors and are connected in series and both of them are connected to the resistor in parallel.
The entire setup is connected to a source of electromagnetic force (emf) and source resistance.
(i)The resistance of circuit when key K is open:
When the key is open, the only resistance left will be the resistance in series with source resistance, hence net resistance =
(ii) The current drawn from the cell when the key k is open.
When the key is open, net resistance = .
By Ohm’s Law, we know that, where is the resistance, is the voltage across its ends and is the current.
.
Since and ,
(iii) The resistance of the circuit when the key k is closed.
When the key K is closed, the current passes through the entire circuit, the will be in parallel with series combination of and
Thus the resistance
The resistance of the circuit when the key k is closed is .
(iv) The current drawn from the cell when the key k is closed.
When the key is closed, net resistance=
Current .
Current drawn when key K is closed is .
Note: Resistance is a measure of the opposition to current flow in an electrical circuit. Resistance is measured in ohms, symbolized by the Greek letter omega. Ohms are named after Georg Simon Ohm (1784-1854), a German physicist who studied the relationship between voltage, current and resistance. He is credited for formulating Ohm's Law.
Formula Used: The formulae used in the solution are given here.
If the resistors are linked in series, the series resistance is articulated as-
If the resistors are linked in parallel, the series resistance is articulated as-
By Ohm’s Law, we know that,
Complete Step by Step Solution: Resistance is the measure of opposition applied by any object to the flow of electric current. A resistor is an electronic constituent that is used in the circuit with the purpose of offering that specific amount of resistance.
If the resistors are linked in series, the series resistance is articulated as-
If the resistors are linked in parallel, the series resistance is articulated as-
For the circuit given above, the resistors
The entire setup is connected to a source of electromagnetic force (emf)
(i)The resistance of circuit when key K is open:
When the key is open, the only resistance left will be the
(ii) The current drawn from the cell when the key k is open.
When the key is open, net resistance =
By Ohm’s Law, we know that,
Since
(iii) The resistance of the circuit when the key k is closed.
When the key K is closed, the current passes through the entire circuit, the
Thus the resistance
(iv) The current drawn from the cell when the key k is closed.
When the key is closed, net resistance=
Current
Current drawn when key K is closed is
Note: Resistance is a measure of the opposition to current flow in an electrical circuit. Resistance is measured in ohms, symbolized by the Greek letter omega. Ohms are named after Georg Simon Ohm (1784-1854), a German physicist who studied the relationship between voltage, current and resistance. He is credited for formulating Ohm's Law.
Recently Updated Pages
Wheatstone Bridge - Working Principle, Formula, Derivation, Application

Young's Double Slit Experiment Step by Step Derivation

JEE Atomic Structure and Chemical Bonding important Concepts and Tips

JEE Amino Acids and Peptides Important Concepts and Tips for Exam Preparation

JEE Electricity and Magnetism Important Concepts and Tips for Exam Preparation

Chemical Properties of Hydrogen - Important Concepts for JEE Exam Preparation

Trending doubts
JEE Main 2025 Session 2: Application Form (Out), Exam Dates (Released), Eligibility, & More

JEE Main 2025: Derivation of Equation of Trajectory in Physics

Electric Field Due to Uniformly Charged Ring for JEE Main 2025 - Formula and Derivation

Electric field due to uniformly charged sphere class 12 physics JEE_Main

Degree of Dissociation and Its Formula With Solved Example for JEE

Displacement-Time Graph and Velocity-Time Graph for JEE

Other Pages
JEE Advanced Marks vs Ranks 2025: Understanding Category-wise Qualifying Marks and Previous Year Cut-offs

JEE Advanced 2025: Dates, Registration, Syllabus, Eligibility Criteria and More

JEE Advanced Weightage 2025 Chapter-Wise for Physics, Maths and Chemistry

JEE Advanced 2025 Notes

Electrical Field of Charged Spherical Shell - JEE

Learn About Angle Of Deviation In Prism: JEE Main Physics 2025
