Magnetic Effect Of Electric Current and JEE Mains PYQ

Magnetic Effect Of Electric Current : 

➡️ Introduction:

The magnetic effect of electric current is a fascinating phenomenon that lies at the heart of various electrical and electronic devices we encounter in our daily lives. This captivating branch of physics unravels the intricate relationship between electricity and magnetism, providing us with valuable insights into the workings of the natural world. In this article, we will delve into the fundamental concepts and keywords associated with the magnetic effect of electric current, unraveling the mysteries behind this invisible force.

➡️ Electromagnetic Induction:

One of the key aspects of the magnetic effect of electric current is electromagnetic induction. Discovered by Michael Faraday in the 19th century, electromagnetic induction states that a changing magnetic field induces an electric current in a conductor and vice versa. This principle forms the basis of various devices such as generators, transformers, and induction coils, which are essential components in power generation and transmission systems.

➡️ Ampere's Law:

Ampere's Law, formulated by André-Marie Ampère, establishes the relationship between a magnetic field and the electric current that generates it. It states that the magnetic field around a current-carrying conductor is directly proportional to the current flowing through the conductor. Ampere's Law provides a quantitative understanding of the magnetic field's strength and enables us to calculate the magnetic field at various points around a conductor.

➡️ Magnetic Field Strength:

The magnetic field strength is a measure of the intensity of the magnetic field at a particular point. It is denoted by the symbol 'B' and is measured in tesla (T) or gauss (G). The magnetic field strength depends on factors such as the current flowing through a conductor, the distance from the conductor, and the medium in which the magnetic field exists. Understanding magnetic field strength is crucial for designing magnetic devices and studying the interaction between magnetic fields and other objects.

➡️ Solenoid and Electromagnet:

A solenoid is a coil of wire wound in the form of a cylinder. When an electric current passes through a solenoid, it generates a magnetic field along its axis. 

Solenoids find applications in various devices, including electromagnetic valves, electric locks, and relays. Moreover, by placing a ferromagnetic material, such as iron, inside a solenoid, we can create an electromagnet. 

Electromagnets are used in electric motors, speakers, MRI machines, and many other technological advancements.

➡️ Right-hand Thumb Rule:

The right-hand thumb rule is a practical tool used to determine the direction of the magnetic field around a current-carrying conductor. According to this rule, if you point your right thumb in the direction of the current, the curled fingers indicate the direction of the magnetic field lines. The right-hand thumb rule simplifies the visualization of magnetic fields and aids in understanding their behavior in different scenarios.

➡️ Fleming's Left-hand Rule:

Fleming's left-hand rule is another valuable tool used to determine the direction of the force experienced by a current-carrying conductor placed in a magnetic field. By aligning the thumb, index finger, and middle finger of your left hand in specific orientations, you can identify the direction of the force, the magnetic field, and the current. This rule is widely employed in analyzing the behavior of electric motors and generators.

➡️ Magnetic Field Lines:

Magnetic field lines are an abstract representation used to visualize and describe the behavior of magnetic fields. These lines form closed loops around a current-carrying conductor or a magnet, and their density represents the strength of the magnetic field at different points. Magnetic field lines never intersect, as they follow a continuous path from the north pole to the south pole of a magnet. By observing the pattern of magnetic field lines, scientists can gain valuable insights into the behavior of magnetic fields.

➡️ Magnetic Flux:

Magnetic flux is a measure of the total magnetic field passing through a given area. It depends on the strength of the magnetic field, the area through which it passes, and the angle between the field and the area. The unit of magnetic flux is the Weber (Wb), and it plays a crucial role in understanding electromagnetic induction and Faraday's law.

➡️ Oersted's Experiment:

Hans Christian Oersted's experiment in 1820 was a groundbreaking discovery that established the relationship between electricity and magnetism. By observing the deflection of a magnetic needle when placed near a current-carrying wire, Oersted demonstrated that electric current produces a magnetic field. This experiment laid the foundation for future developments in electromagnetism and transformed our understanding of the natural world.

➡️ Applications of Electromagnetic Induction:

Electromagnetic induction has numerous practical applications in our modern lives. Generators, which convert mechanical energy into electrical energy, rely on electromagnetic induction principles. Transformers utilize electromagnetic induction to change the voltage levels in power distribution systems efficiently. Induction coils are used in wireless charging systems, metal detectors, and even medical devices like magnetic resonance imaging (MRI) machines. The applications of electromagnetic induction are vast and continue to revolutionize technology.

➡️ Conclusion:

The magnetic effect of electric current, as explored through the keywords mentioned above, offers a captivating journey into the intricate relationship between electricity and magnetism. From understanding the fundamental principles of electromagnetic induction and Ampere's Law to visualizing magnetic fields through the right-hand thumb rule and Fleming's left-hand rule, these concepts form the building blocks of modern technology. By grasping the magnetic effect of electric current, we unlock the potential to design innovative devices, harness sustainable energy, and unravel the mysteries of the natural world.

➡️ Remember, the magnetic effect of electric current is not just confined to the pages of a textbook. It surrounds us in everyday life, shaping the technology we rely on and inspiring further exploration into the realms of electromagnetism. So, embrace the invisible force of magnetism and embark on a journey of discovery through the captivating world of the magnetic effect of electric current.

➡️ Here are a few sample PYQ (Previous Year Question) questions related to the magnetic effect of electric current in JEE (Joint Entrance Examination) Mains:

1). JEE Mains 2020 (January Shift 1):

A current I is flowing in a wire of length L. The wire is bent in the shape of a circular loop of radius R. The magnitude of the magnetic field at the center of the loop is given by:

(A) μ₀I/2πR

(B) μ₀I/4πR

(C) μ₀I/πR

(D) μ₀I/8πR

Solution:

The magnetic field at the center of a circular loop due to the current flowing through it can be calculated using the formula:

B = (μ₀I)/(2R)

Here, I is the current flowing through the wire and R is the radius of the loop.

Answer: (A) μ₀I/2πR

2). JEE Mains 2019 (January Shift 1):

A long straight wire carries a current I. A circular loop of wire is placed around the straight wire with the same center and lies in the same plane. If the current in the loop is increased, the magnetic field at the center of the loop:

(A) Increases

(B) Decreases

(C) Remains the same

(D) Becomes zero

Solution:

According to Ampere's law, the magnetic field at the center of a circular loop due to the current flowing through it is directly proportional to the current passing through the loop.

Therefore, if the current in the loop is increased, the magnetic field at the center of the loop will also increase.

Answer: (A) Increases

3). JEE Mains 2018 (April Shift 1):

A circular loop of radius R carries a current I. The magnetic field at the center of the loop is B. If the radius of the loop is doubled and the current is halved, the magnetic field at the center will be:

(A) B/4(

(B) B/2

(C) B

(D) 2B

Solution:

The magnetic field at the center of a circular loop due to the current flowing through it can be calculated using the formula:

B = (μ₀I)/(2R)

When the radius of the loop is doubled (2R) and the current is halved (I/2), the magnetic field at the center can be calculated as:

B' = (μ₀(I/2))/(2(2R)) = (μ₀I)/(4R) = B/4

Answer: (A) B/4

4). JEE Mains 2017 (April Shift 2):

A wire in the shape of a regular hexagon of side 'a' carries a current 'I'. The magnitude of the magnetic field at the center of the hexagon is given by:

(A) μ₀I/4a

(B) μ₀I/2a

(C) μ₀I/a

(D) μ₀I/√3a

Solution:

The magnetic field at the center of a regular polygon due to the current flowing through it can be calculated using the formula:

B = (μ₀I)/(2a)

Here, I is the current flowing through the wire and a is the side length of the hexagon.

Answer: (B) μ₀I/2a

5). JEE Mains 2016 (April Shift 1):

Two identical wires, each carrying a current 'I', are placed parallel to each other at a distance 'd' apart. The magnetic field at a point midway between the wires is given by:

(A) μ₀I/4πd

(B) μ₀I/2πd

(C) μ₀I/πd

(D) μ₀I/8πd

Solution:

According to Ampere's law, the magnetic field at a point midway between two parallel wires carrying currents in the same direction can be calculated using the formula:

B = (μ₀I)/(2πd)

Here, I is the current flowing through each wire and d is the distance between the wires.

Answer: (B) μ₀I/2πd

Please note that these solutions are provided for reference purposes, and it is recommended to refer to official JEE Mains practice papers and past year question papers for comprehensive preparation.