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ELECTROMAGNETIC INDUCTION - EMI in One Shot - All Concepts & PYQs | NEET Physics Crash Course

Competition Wallah・2 minutes read

The importance of understanding magnetic flux and electromagnetic induction is emphasized, with detailed explanations on Faraday's laws and induced EMF. Practical examples and calculations are provided to illustrate concepts such as mutual inductance, self-inductance, and induced currents in coils, highlighting the significance of flux linkage and the relationship between changing magnetic fields and induced electric fields.

Insights

  • The importance of understanding magnetic flux and its formula, with Weber as the unit of measurement.
  • Faraday's Laws of electromagnetic induction are introduced, emphasizing generating current without batteries.
  • The significance of changing magnetic flux for inducing EMF and current is reiterated.
  • The impact of factors like magnetic field changes, coil area, and coil turns on flux calculations.
  • Mutual inductance between coils and the relationship between primary and secondary currents are explored.
  • The concept of induced electric fields due to changing magnetic fields and the formation of closed loops is detailed.

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Recent questions

  • What is the importance of understanding magnetic flux?

    Understanding magnetic flux is crucial in various scenarios as it plays a key role in electromagnetic induction. The concept of flux helps in generating current without a battery, as explained by Faraday's laws. It involves changes in magnetic fields and area, affecting the induction of EMF and current. Flux calculations are essential for coils, solenoids, and mutual inductance between two coils. Knowing the formula for flux and its variations due to changes in magnetic fields or area is fundamental for grasping electromagnetic concepts. Overall, comprehending magnetic flux is vital for understanding electromagnetic phenomena and their practical applications.

  • How can one calculate induced EMF in a coil?

    The formula for induced EMF in a coil is e = -L di/dt, where L represents the self-inductance of the coil. This formula indicates that the induced EMF is proportional to the rate of change of current flowing through the coil. By considering the self-inductance value and the time derivative of the current, one can calculate the induced EMF in the coil. Understanding this formula is essential for analyzing the behavior of coils in electromagnetic systems and predicting the effects of changing currents on induced EMF.

  • What is mutual inductance between two coils?

    Mutual inductance is a phenomenon where a change in current in one coil induces a current in a neighboring coil. It showcases the interdependence between the primary and secondary coils, where the flux in the secondary coil is directly influenced by the primary current. The coefficient of mutual inductance (m) quantifies this relationship, highlighting how changes in one coil affect the induced EMF in the other. Calculating mutual inductance involves considering factors like the number of turns, radius, and orientation of the coils, providing insights into the coupling between the coils and the induced currents.

  • How does changing magnetic fields lead to induced electric fields?

    Changing magnetic fields result in the creation of induced electric fields, following Maxwell's equations. These changing fields induce electric fields that form closed loops, showcasing the relationship between magnetic and electric phenomena. The concept of induced electric fields is crucial in understanding electromagnetic interactions and the generation of eddy currents. By comprehending how changing magnetic fields lead to induced electric fields, one can grasp the underlying principles of electromagnetic induction and its applications in various systems.

  • What is the significance of understanding self-inductance in coils?

    Self-inductance in coils is essential for predicting and analyzing the behavior of coils in electromagnetic systems. It involves creating a magnetic field due to the current flowing through the coil, influencing the induced EMF and current. Understanding self-inductance helps in calculating the induced EMF based on the rate of change of current, as indicated by the formula e = -L di/dt. By grasping the concept of self-inductance, one can effectively manage and control current flow in coils, ensuring efficient operation in electromagnetic devices and circuits.

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Summary

00:00

"NEET Preparation: Magnetic Flux and Practice Sheets"

  • Manzil series sixth starting from tomorrow, zero spamming requested
  • Anjali, Nitesh, Sharad, Utsav, Sumita, Siddharth, Yamini Gupta, Darpan Bhatt, Khushboo present
  • Pranam to Prayas 2.0 with excellent faculties, hard work, and trending videos
  • Prayas 2.0 launch timing approximate, after JE Fourth Atom
  • Free batches like Sankalp, Warrior, NDA available with revenue from ads
  • Lecture duration 45 minutes, NEET crash course Day 35 on Electromagnetic Induction
  • Practice sheet download available on Physics Wala's mobile app for NEET preparation
  • Importance of watching lectures and solving practice sheet questions for NEET preparation
  • Magnetic flux formula discussed, unit of magnetic flux is Weber
  • Explanation of flux in non-uniform fields, integration of flux in non-uniform fields
  • Upcoming Arjuna 2.2 batch with improvements, completion of syllabus revision ongoing
  • Explanation of flux in coils with n turns, total flux calculation for multiple coils
  • Solving a question on magnetic flux for a circular disk in a uniform magnetic field at a 60-degree angle

14:02

Understanding Faraday's Laws of Electromagnetic Induction

  • The square of 0.2 is 0.04, while the square of cos 60 is 0.5.
  • The magnetic flux is a key concept, with the first point emphasizing the importance of understanding it.
  • The story of magnetic flux is further elaborated, stressing the significance of the flux in different scenarios.
  • Faraday's laws of electromagnetic induction are introduced, highlighting the method of generating current without a battery.
  • Faraday's emphasis on converting mechanical energy into electrical energy is explained through his experiments.
  • The process of inducing EMF in a conductor through changes in magnetic flux is detailed.
  • The importance of a closed circuit for inducing current is emphasized, along with the role of potential difference.
  • Faraday's law is reiterated, focusing on the necessity of changing magnetic flux for inducing EMF.
  • The rate of change in magnetic flux is crucial for generating EMF and current, as explained by Faraday's second law.
  • Faraday's law underscores the relationship between mechanical energy changes and the generation of electrical energy through induced current.

29:04

Factors Affecting Flux in Coils

  • The formula for flux is b a k theta, where changes in b, a, or theta can lead to flux changes.
  • If the magnetic field changes, the flux in a coil will change accordingly.
  • Changes in the radius of a coil can affect the area, leading to flux alterations.
  • Rotating a coil at an angle between the area vector and magnetic field can induce changes in flux.
  • The angle between the magnetic field and area vector determines the flux.
  • The number of turns in a coil affects the flux calculation.
  • Induced EMF in a coil can be calculated using the formula e = d f / dt.
  • A coil with a decreasing radius will experience changes in flux due to the shrinking area.
  • The reduction in effective area of a coil will result in a decrease in flux.
  • The number of turns in a coil must be considered when calculating induced EMF.

44:37

Calculating Induced Current and Charge in Solenoid

  • The rate of change is negative, indicated by d/dt-2425, showing a decrease in something.
  • The formula for finding the radius when it is 2 centimeters is discussed, with a clear explanation of the process.
  • The magnetic field, beta b, is calculated to be 0.025, which is equivalent to 25/1000.
  • The power of dt1-3 beta is determined, leading to a final result of 3.2 pi microvolts.
  • The process of calculating induced charge, EMF, and current is detailed, emphasizing the importance of understanding the formula.
  • The concept of integration is introduced to calculate the area under a curve, crucial for determining the charge.
  • The question involves analyzing the magnitude of induced current in a solenoid coil with a resistance of 10 ohms.
  • The total charge flowing through the coil is calculated by determining the change in flux and the number of turns.
  • The magnetic field inside the solenoid is discussed, focusing on the flux and the area involved in the calculation.
  • The process of finding the total charge flowing through the coil is explained, emphasizing the importance of understanding the changing flux and the number of turns.

01:04:22

Calculating Current Direction in Electromagnetic Scenarios

  • The text discusses calculations involving unit length, constant radius, turns, and the value of pi.
  • It mentions determining the radius and weight when the number of turns is 100.
  • The text delves into calculating the charge q using delta f and r, along with the values of delta i and resistance.
  • It explains the concept of induced current and the direction of current based on Lens Law.
  • The text emphasizes the importance of opposing the cause that produces induced current.
  • It touches on Faraday's Law and Lens Law based on conservation of energy.
  • The text provides guidance on determining the direction of induced current in various scenarios.
  • It explains how to determine the direction of induced current when the magnetic field is increasing or decreasing.
  • The text discusses the behavior of a current-carrying loop and the direction of current based on the North Pole's movement.
  • It elaborates on the concept of opposing the cause to maintain equilibrium in induced current situations.

01:20:39

Navigating Life's Currents Towards Success

  • The text discusses the importance of happiness and moving forward in life to achieve goals.
  • It mentions the significance of studying and not wasting time by staying awake all night.
  • The text emphasizes the need to be aware of one's surroundings and the direction of currents.
  • It talks about the importance of knowing where the current is coming from and the significance of the North and South Poles.
  • The text mentions the necessity of understanding the clockwise and anti-clockwise directions of currents.
  • It discusses the concept of repulsion between poles and the impact of magnetic fields on currents.
  • The text delves into the topic of induced currents and the effects of magnetic fields on falling objects.
  • It explains the relationship between magnetic fields and induced currents due to gravity.
  • The text discusses the direction of currents induced by changing magnetic fields and the concept of electromagnetic induction.
  • It concludes with a practical example involving a coil in a magnetic field and the calculation of induced current and voltage.

01:38:39

Voltage, Magnetic Fields, and Current Control

  • The text discusses the concept of voltage and magnetic fields, mentioning the creation of a 20-volt SU.
  • It delves into the manipulation of magnetic fields to control current direction, specifically focusing on anti-clockwise movement.
  • The text highlights the dominance of larger voltages in determining current direction.
  • It explains the interaction between two opposing voltages and their impact on current flow.
  • The discussion shifts to induced EMF and current in a rotating coil within a magnetic field.
  • It emphasizes the relationship between coil rotation, area vector movement, and flux change in inducing EMF.
  • The text explores the formula for induced EMF and current, emphasizing the constant factors involved.
  • It transitions to the application of these principles in an AC generator, explaining the generation of alternating current.
  • The text touches on the concept of maximum EMF and current in a rotating coil within a magnetic field.
  • It concludes with a discussion on the relationship between current and EMF in a resistive circuit, highlighting phase differences and direction changes.

02:11:43

Motional EMF and Induced Current Formulas

  • When a beta rod cuts through magnetic field lines, EMF is generated in the rod.
  • The formula for motional EMF is e = Bvl, where v is perpendicular to B and L.
  • The direction of EMF can be determined using the right-hand rule, with the thumb pointing in the direction of motion.
  • The formula for EMF is commonly used when velocity is perpendicular to the magnetic field.
  • The direction of induced current can be found using the right-hand rule, with the thumb pointing in the direction of motion.
  • In the case of a straight line conductor moving in a magnetic field, the current can be calculated using the formula e = Bvl/R.
  • The displacement length in the formula e = Bvl is the vector length from the initial to final position.
  • In a scenario where a conducting ring falls in a horizontal magnetic field, the potential difference developed across the ring can be calculated using the formula e = Bv.
  • The induced EMF in a scenario where a conducting ring falls in a horizontal magnetic field can be found using the formula e = 2BvR.
  • When finding the induced EMF in a scenario where a conducting ring falls in a horizontal magnetic field, the vector length connecting the ends of the ring should be considered.

02:28:57

Magnetic Field Effects on Induced EMF

  • The total length becomes 2ls theta / 2 velocity.
  • The magnetic field is perpendicular to vector l.
  • The magnetic field is directed along the negative root.
  • The induced EMF will not remain constant for circular and elliptical loops due to changes in vector length.
  • The length of the rod remains constant as it moves with constant velocity.
  • The conducting rod slides at a constant velocity v on two parallel conducting rails in a uniform magnetic field.
  • The induced EMF in the rod is determined by the velocity, length, and magnetic field perpendicular to the rod.
  • The force required to move the rod at a constant velocity is equal to the magnetic force acting on it.
  • The power input is calculated by multiplying the magnetic force by the velocity.
  • The output power in the resistance is equal to the square of the current flowing through it.

02:49:46

"Rod motion and magnetic fields explained"

  • No force needed to move the rod edge indicated with a constant speed.
  • The direction of the magnetic field inside is perpendicular to the motion.
  • Current will flow through the rod, with a resistance of 3 ohms.
  • The internal resistance of the cell is not necessary for the current flow.
  • The force needed to move the rod is determined by the external force.
  • The power output is calculated by applying the external force in the same direction as the velocity.
  • The EMF across the ends of the rod is determined by the rotating rod's characteristics.
  • The rotating rod's velocity increases with distance from the center of mass.
  • The expression for the velocity of the center of mass is linear.
  • The velocity of the center of mass is calculated by dividing the velocity of a point by the length.

03:09:29

Understanding Induced Currents in Circuits

  • The text discusses mathematical equations and calculations involving fractions and distances.
  • It mentions the concept of center of mass and velocity in relation to distances and lengths.
  • The text delves into the topic of magnetic fields and motion within them, emphasizing the direction of magnetic fields and the impact of changing currents.
  • It explains the phenomenon of self-induction in circuits due to changing currents, inducing emf, and the direction of induced currents.
  • The text provides examples and scenarios to illustrate the concepts of self-induction and induced currents.
  • It highlights the importance of understanding the direction of induced currents in relation to growing or decreasing currents.
  • The text discusses the direction of induced currents in circuits and the logic behind opposing the causes that produce them.
  • It emphasizes the role of inductors in inducing emf and the significance of understanding the direction of induced currents.
  • The text concludes with a focus on the logic behind induced currents opposing the causes that produce them.
  • It encourages understanding the concepts of self-induction and induced currents through practical examples and explanations.

03:30:31

"Understanding Self-Inductance and Magnetic Fields"

  • Current direction is determined by the positive terminal of the battery.
  • Eating from the same plate induces self-induced EMF.
  • Self-inductance is confident in creating a magnetic field due to current.
  • Flux is directly proportional to the magnetic field.
  • Magnetic field and flux are proportional to the current.
  • The unit of self-inductance is Henry.
  • Self-inductance depends on the number of turns, length, and radius of the coil.
  • The formula for induced EMF in an inductor is e = -L di/dt.
  • The current in a coil varies with time, affecting the induced EMF.
  • Calculating potential difference involves considering the direction of current flow and the path taken.

03:53:07

Self-Study Physics: Inductance and Mutual Induction

  • Vinod Jaiswal refers to himself as a child and discusses studying for two years in 11th and 12th grade.
  • The concept of self-study is discussed, with a focus on understanding and actions taken during this period.
  • The relationship between current, induction, and support is explained, emphasizing the positive and negative aspects.
  • The process of creating a battery and managing current flow is detailed, including the direction and magnitude of the electric field.
  • The importance of self-inductance in coils is highlighted, with a break taken before delving into further topics.
  • The specifics of self-inductance in coils, solenoids, and mutual inductance between two coils are explored.
  • Practical calculations are demonstrated, such as determining the self-inductance value based on the number of turns and dimensions of the coil.
  • The process of inducing EMF in a solenoid due to changing current is explained, with a focus on calculations involving length and radius.
  • Mutual induction between two coils is discussed, detailing how changing current in one coil induces current in the other.
  • The direction of induced current in the secondary coil due to changes in the primary coil is clarified, emphasizing the anti-clockwise direction when viewed from above.

04:24:56

Mutual inductance: Current induction between coils

  • Mutual inductance is the phenomenon where a change in current in one coil induces a current in a neighboring coil.
  • The experiment on mutual inductance reveals the magical induction of current between coils.
  • The induced current in a coil is directly proportional to the magnetic field created by the primary current.
  • The coefficient of mutual inductance (m) is crucial in understanding the relationship between primary and secondary currents.
  • The flux in the secondary coil is dependent on the primary current, showcasing the interdependence between the two.
  • Faraday's Law explains that the induced EMF in the secondary coil is directly proportional to the change in flux over time.
  • Calculating mutual inductance involves determining the change in current over time, as seen in the example of current changing from 5A to 2A in 300 milliseconds.
  • The maximum induced EMF in the secondary coil is determined by the amplitude of the equation involving mutual inductance and angular frequency.
  • Mutual inductance between two concentric coils is influenced by the number of turns, radius, and the orientation of the coils.
  • Understanding mutual inductance aids in calculating induced EMF in coils, considering factors like the number of turns and the radius of the coils.

04:45:55

Understanding Mutual Inductance and Flux Linkage

  • The text discusses the calculation of flux linkage and coupling in coils, emphasizing the importance of mutual inductance.
  • It explains the concept of flux linkage and the significance of coupling in coils, with formulas provided for calculations.
  • The text delves into the impact of mutual inductance on current induction and the necessity of flux linkage for mutual inductance.
  • It highlights the conditions where coupling and mutual inductance are absent, leading to zero values for k and m.
  • The text elaborates on the scenario where coils with self-inductance are placed close together, resulting in effective flux linkage.
  • It introduces the concept of induced electric fields due to changing magnetic fields, emphasizing the formation of closed loops.
  • The text discusses the relationship between changing magnetic fields and induced electric fields, following Maxwell's equations.
  • It concludes by explaining how changing magnetic fields lead to the creation of eddy currents and induced electric fields in closed loops.
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