Electromagnetism (SAQs)

Physical Science | 10. Electromagnetism – SAQs:
Welcome to SAQs in Chapter 10: Electromagnetism. This page contains the most Important FAQs for Short Answer Questions in this Chapter. Each answer is provided in simple English, with a Telugu explanation, and formatted according to the exam style. This will support your preparation and help you secure top marks in your exams.

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SAQ-1 : List out the materials required for Oersted experiment and mention the precautions to be taken in the experiment ?

Introduction

The Oersted experiment is a fundamental experiment in the world of physics, demonstrating the relationship between electricity and magnetism. Hans Christian Oersted first discovered that a current-carrying wire produces a magnetic field around it. To recreate this experiment, specific materials and precautions are necessary.

Materials Needed for the Oersted Experiment

1. Thermocoal Sheet:
   Acts as a base for setting up the experiment, providing insulation from any conducting surfaces.
2. Wooden Sticks:
   Used to elevate and hold the copper wire in place, ensuring it’s suspended and does not touch other surfaces.
3. Copper Wire (24 Gauge):
   A conductor through which electricity will pass, demonstrating the magnetic effect of the current.
4. Battery:
   Provides the electric current necessary for the experiment.
5. Key (or Switch):
   Allows the experimenter to control when the current is flowing through the wire.
6. Magnetic Compass:
   Essential for observing the magnetic effect of the current. The needle will deflect when close to the current-carrying wire.

Key Precautions to Consider

1. Wire Placement:
   Ensure that the copper wire is securely positioned through the slits of the wooden sticks and is taut. A tight wire helps in producing a more discernible effect on the magnetic compass.
2. Circuit Integrity:
   Before starting the experiment, ensure all components of the circuit, including the battery, key, and wire connections, are correctly arranged and connected.
3. Avoid External Magnetic Fields:
   To get accurate results, perform the experiment away from other magnets or devices producing magnetic fields, as they might interfere with the compass readings.
4. Use Fresh Batteries:
   Make sure the battery used is not depleted, as a weak battery might not produce a strong enough current to observe the desired magnetic effect.
5. Handle Compass Carefully:
   Ensure the magnetic compass is in good working condition and is free from any interference to observe clear deflections.

Summary

The Oersted experiment is crucial for understanding the relationship between electricity and magnetism. By ensuring that you have the right materials and follow necessary precautions, the experiment can be performed successfully, highlighting the interplay between electric currents and magnetic fields.

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SAQ-2 : Compare the magnetic field lines of force formed around a current carrying solenoid with the magnetic field lines of force of a bar magnet.

Introduction

Magnetic fields play a crucial role in our understanding of electromagnetism. Two important sources of magnetic fields are bar magnets and solenoids. This piece sheds light on how the magnetic field lines generated by these two entities compare.

Magnetic Field Lines of a Bar Magnet:

1. Closed Loops: Just like all magnetic fields, the field lines of a bar magnet form closed loops.
2. Outside Direction: On the outside, field lines travel from the north pole to the south pole.
3. Inside Direction: Intriguingly, within the bar magnet, these field lines appear to move from the south pole to the north pole.
4. Similarity to Solenoid: The field lines around a bar magnet closely resemble those formed around a solenoid.
5. Polar Concentration: The poles of the bar magnet (north and south) have a higher concentration of field lines.
6. Internal Field Lines: It’s not feasible to observe or trace the field lines inside the physical material of a bar magnet.

Magnetic Field Lines of a Solenoid:

1. Closed Loops: Field lines around a solenoid also form closed loops.
2. Outside Direction: When examining the outside of the solenoid, field lines flow from the north end to the south end.
3. Inside Direction: Inside the solenoid, the field lines travel from the south end to the north end.
4. Similarity to Bar Magnet: The field lines of a solenoid are akin to those seen around a bar magnet.
5. Polar Concentration: Just like in bar magnets, there’s a denser concentration of field lines at the poles (ends) of the solenoid.
6. Internal Field Lines: Unlike bar magnets, one can observe and trace the field lines inside the solenoid, typically when it’s filled with air or another medium.

Summary

While bar magnets and solenoids both produce magnetic fields, the way they generate and the characteristics of these fields are distinct. The ability to trace field lines within a solenoid, for instance, makes it different from a bar magnet. However, their external field patterns are strikingly similar, leading to their often interchangeable use in various applications. Understanding these differences and similarities can be crucial in both theoretical and practical contexts in the realm of electromagnetism.

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SAQ-3 : What happens when magnetic flux passing through a coil changes continuously? Where does this process is used ?

Introduction

Magnetic flux plays a fundamental role in generating electrical currents in coils. When this flux undergoes changes, it results in various phenomena which have a wide range of applications.

Magnetic Flux Change and Its Effect:

Induced Current: If magnetic flux through a coil changes continuously, an electric current, often termed as “induced current”, will be generated within that coil. This phenomenon is due to Faraday’s law of electromagnetic induction.

Applications:

This principle of changing magnetic flux to induce current has multiple practical applications, such as:

1. Induction Stoves:
   These stoves utilize the induction principle to heat up cookware by producing an alternating magnetic field, which induces a current in the cookware.
2. ATM Cards:
   Magnetic stripe cards, like ATM or credit cards, store data in magnetic stripes. When these cards are swiped, the change in magnetic flux induces a current in the card reader, which then reads the stored data.
3. Magnetic Scanners:
   Magnetic scanners, used in stores and libraries, detect changes in magnetic flux to read tags and labels.
4. Security Systems:
   Many entrance and exit doors in security zones use this principle. When a person with a tagged item (which can change the magnetic flux) tries to pass through, the change in flux is detected, triggering an alarm or other security measures.

Summary

The continuous change in magnetic flux and the consequent induced current have significant implications in the real world. From cooking our food with induction stoves to ensuring security with advanced door systems, the process of electromagnetic induction, stemming from changing magnetic flux, is a cornerstone of modern technological applications.