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Test: Magnetic Effects of Electric Current - 1 - UPSC MCQ


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30 Questions MCQ Test Science & Technology for UPSC CSE - Test: Magnetic Effects of Electric Current - 1

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Test: Magnetic Effects of Electric Current - 1 - Question 1

An electric fuse prevents damage to the appliances and circuits due to ____.

Detailed Solution for Test: Magnetic Effects of Electric Current - 1 - Question 1

An electric fuse prevents damage to the appliances and circuits due to short-circuiting, which can occur when the live wire and the neutral wire come into direct contact, causing an abrupt increase in current flow.

Test: Magnetic Effects of Electric Current - 1 - Question 2

What defines a solenoid in the context of magnetic fields?

Detailed Solution for Test: Magnetic Effects of Electric Current - 1 - Question 2

In the context of magnetic fields, a solenoid is defined as a coil of many circular turns of insulated wire. Solenoids are crucial components in electromagnets and various electrical devices due to their ability to generate strong and uniform magnetic fields.

Test: Magnetic Effects of Electric Current - 1 - Question 3

Assertion (A): Magnetic field lines around a current-carrying straight conductor form closed loops.

Reason (R): Magnetic monopoles do not exist in nature.

Detailed Solution for Test: Magnetic Effects of Electric Current - 1 - Question 3
  • The Assertion is correct. Magnetic field lines always form closed loops around a current-carrying conductor.
  • The Reason is also correct as magnetic monopoles, isolated magnetic charges (separate north or south poles), have not been observed in nature.
  • However, the Reason does not provide a direct explanation for the Assertion. The formation of closed loops in magnetic fields is a consequence of the fundamental property of magnetic fields, not directly related to the absence of magnetic monopoles.
  • Therefore, the correct option is revealed through detailed examination.
Test: Magnetic Effects of Electric Current - 1 - Question 4

What did Hans Christian Oersted discover accidentally?

Detailed Solution for Test: Magnetic Effects of Electric Current - 1 - Question 4

Hans Christian Oersted accidentally discovered the deflection of a compass needle near a metallic wire when an electric current passed through it, revealing the relationship between electricity and magnetism.

Test: Magnetic Effects of Electric Current - 1 - Question 5

What is the purpose of the earth wire in a domestic electric circuit?

Detailed Solution for Test: Magnetic Effects of Electric Current - 1 - Question 5
  • The earth wire in a domestic electric circuit is primarily installed to protect against electric shocks. It provides a low-resistance path for the current, ensuring that any leakage of current to the metallic body of an appliance keeps its potential equal to that of the earth.
  • This safety measure prevents users from experiencing severe electric shocks.
Test: Magnetic Effects of Electric Current - 1 - Question 6

Assertion (A): A metallic wire carrying an electric current has associated with it a magnetic field.

Reason (R): The field lines about the wire consist of a series of concentric circles whose direction is given by the right-hand rule.

Detailed Solution for Test: Magnetic Effects of Electric Current - 1 - Question 6
  • The Assertion is correct. When a metallic wire carries an electric current, it generates a magnetic field around it. This phenomenon is a fundamental aspect of electromagnetism.
  • The Reason is also correct. The magnetic field around the wire indeed forms concentric circles, and the direction of these circles is determined by the right-hand rule.
  • However, the Reason statement is not the correct explanation of the Assertion. While both statements are individually true, the Reason does not directly explain why a metallic wire carrying an electric current produces a magnetic field.
Test: Magnetic Effects of Electric Current - 1 - Question 7

Assertion (A): The magnetic field lines around a bar magnet are closed curves.

Reason (R): Inside the magnet, the direction of field lines is from its south pole to its north pole.

Detailed Solution for Test: Magnetic Effects of Electric Current - 1 - Question 7
  • Assertion (A) is true; magnetic field lines around a bar magnet are indeed closed curves.
  • Reason (R) is also true; inside the magnet, the direction of field lines runs from its south pole to its north pole.
  • However, the Reason does not correctly explain Assertion, as the closure of field lines is a consequence of the overall magnetic field configuration rather than just the direction of the field lines inside the magnet.
Test: Magnetic Effects of Electric Current - 1 - Question 8
Choose the correctly matched pair:
Detailed Solution for Test: Magnetic Effects of Electric Current - 1 - Question 8
  • Option A is correctly matched. The right-hand thumb rule is used to determine the direction of the magnetic field around a current-carrying straight conductor. According to this rule, if you hold the conductor in your right hand such that your thumb points in the direction of the current, your fingers will curl around the conductor in the direction of the magnetic field lines.
  • Option B is incorrect. The right-hand thumb rule specifically applies to a straight conductor, not a circular loop. For a current-carrying circular loop, the magnetic field lines form concentric circles at every point of the loop and appear as straight lines at the center.
  • Option C is incorrect. Maxwell's corkscrew rule is another way of describing the right-hand thumb rule for determining the direction of the magnetic field around a current-carrying conductor. It does not describe the motion of charged particles in a magnetic field.
  • Option D is incorrect. Magnetic field lines never intersect each other. If they did, it would imply that there are two different directions of the magnetic field at the point of intersection, which is not possible.
Test: Magnetic Effects of Electric Current - 1 - Question 9

Why does a compass needle get deflected when brought near a _____?

Detailed Solution for Test: Magnetic Effects of Electric Current - 1 - Question 9

A compass needle is affected by magnetic fields. When it is brought near a bar magnet, the magnetic field of the bar magnet causes the needle to deflect. A plastic rod does not produce a magnetic field, so it will not affect the compass needle.

Test: Magnetic Effects of Electric Current - 1 - Question 10

The magnetic field is stronger where the field lines are ______.

Detailed Solution for Test: Magnetic Effects of Electric Current - 1 - Question 10

The magnetic field is stronger where the field lines are closer together, indicating a higher concentration of magnetic force in that region. This closeness of field lines signifies a greater force acting on the poles of another magnet placed in that area.

Test: Magnetic Effects of Electric Current - 1 - Question 11

In Fleming’s left-hand rule the thumb indicates the direction of

Detailed Solution for Test: Magnetic Effects of Electric Current - 1 - Question 11

In Fleming’s left-hand rule the thumb indicates the direction of mechanical force acting on the conductor. The forefinger points in the direction of magnetic field and the central finger in the direction of current flowing in the conductor.

Test: Magnetic Effects of Electric Current - 1 - Question 12

Which property of a proton can change while it moves freely in a magnetic field?

Detailed Solution for Test: Magnetic Effects of Electric Current - 1 - Question 12

When a proton moves freely in a magnetic field, its velocity can change. This change occurs due to the interaction between the magnetic field and the moving charge, leading to alterations in the proton's direction and speed.

Test: Magnetic Effects of Electric Current - 1 - Question 13

Assertion (A): The deflection of a compass needle decreases as the distance from a current-carrying conductor increases.

Reason (R): The magnetic field produced by a given current in the conductor decreases as the distance from it increases.

Detailed Solution for Test: Magnetic Effects of Electric Current - 1 - Question 13
  • The Assertion is true as per the information provided in the text. As the distance from a current-carrying conductor increases, the deflection of a compass needle does indeed decrease.
  • The Reason is true. The magnetic field produced by a given current in the conductor decreases as the distance from it increases, as explained in the content.
    The correct answer should be A, as the weakening of the magnetic field directly causes the reduction in deflection. The original solution is correct, but the Reason does directly explain the Assertion.
Test: Magnetic Effects of Electric Current - 1 - Question 14

A metallic wire carrying an electric current has associated with it a _______.

Detailed Solution for Test: Magnetic Effects of Electric Current - 1 - Question 14

A metallic wire carrying an electric current generates a magnetic field around it. This phenomenon is a fundamental concept in electromagnetism, demonstrated by the right-hand rule.

Test: Magnetic Effects of Electric Current - 1 - Question 15

Overloading is due to

Detailed Solution for Test: Magnetic Effects of Electric Current - 1 - Question 15

Overloading occurs when there is any fault in the appliances or the insulation of wire got damaged. It also occurs when there is sudden hike in supply voltage.

Test: Magnetic Effects of Electric Current - 1 - Question 16

What is the name of the rule that determines the direction of magnetic field lines around a current-carrying straight conductor?

Detailed Solution for Test: Magnetic Effects of Electric Current - 1 - Question 16
  • The correct answer is the Right-hand thumb rule, which helps in determining the direction of magnetic field lines around a current-carrying straight conductor.
  • When the thumb points in the direction of the current, the fingers wrap around the conductor in the direction of the magnetic field lines.
Test: Magnetic Effects of Electric Current - 1 - Question 17

Assertion (A): When a circular loop of wire lies in the plane of the table with current passing through it clockwise, the magnetic field direction inside and outside the loop can be determined using the right-hand rule.

Reason (R): The magnetic field in a given region is uniform.

Detailed Solution for Test: Magnetic Effects of Electric Current - 1 - Question 17
  • The assertion is correct. When a circular loop of wire lies in the plane of the table with current passing through it clockwise, the right-hand rule helps determine the direction of the magnetic field inside and outside the loop. This rule states that if the thumb points in the direction of the current, the fingers curl in the direction of the magnetic field lines.
  • Regarding the reason, it is also correct. A uniform magnetic field means that the field strength and direction are consistent throughout the region in question.
  • However, the reason does not directly explain the assertion. While a uniform magnetic field is mentioned in the reason, it does not serve as a direct explanation for how the right-hand rule is used to determine the magnetic field direction around a current-carrying loop.
  • Therefore, the correct answer is Option B: If both Assertion and Reason are true but Reason is not the correct explanation of Assertion.
Test: Magnetic Effects of Electric Current - 1 - Question 18

What is the purpose of a fuse in an electrical circuit?

Detailed Solution for Test: Magnetic Effects of Electric Current - 1 - Question 18
  • A fuse in an electrical circuit serves the crucial role of safeguarding the circuit from short-circuiting or overloading. It does so by breaking the circuit when excessive current flows through it, thereby preventing damage to the components and ensuring safety.
  • Fuses are designed to melt and interrupt the flow of current when the current exceeds a safe level, thus protecting the circuit from potential hazards.
Test: Magnetic Effects of Electric Current - 1 - Question 19

What determines the pattern of the magnetic field generated by a current through a conductor?

Detailed Solution for Test: Magnetic Effects of Electric Current - 1 - Question 19

The pattern of the magnetic field generated by a current through a conductor is primarily determined by the shape of the conductor. Different shapes of conductors can produce varied patterns of magnetic fields based on their geometries and orientations.

Test: Magnetic Effects of Electric Current - 1 - Question 20

Earth wire carries

Detailed Solution for Test: Magnetic Effects of Electric Current - 1 - Question 20

A "groundingwire on the other hand is a safety wire that has intentionally been connected to earth. The grounding wire does not carry electricity under normal circuit operations. It's purpose is to carry electrical current only under short circuit or other conditions that would be potentially dangerous.

Test: Magnetic Effects of Electric Current - 1 - Question 21

What do concentric circles around a straight conducting wire represent?

Detailed Solution for Test: Magnetic Effects of Electric Current - 1 - Question 21

The concentric circles around a straight conducting wire represent the magnetic field lines produced by the electric current flowing through the wire. These lines indicate the direction and strength of the magnetic field surrounding the wire.

Test: Magnetic Effects of Electric Current - 1 - Question 22

What is the primary function of an electric fuse in a circuit?

Detailed Solution for Test: Magnetic Effects of Electric Current - 1 - Question 22

An electric fuse plays a crucial role in preventing damage to appliances and circuits caused by overloading. When there is an abrupt increase in current due to short-circuiting or other faults, the fuse melts to break the circuit, safeguarding the system from potential harm.

Test: Magnetic Effects of Electric Current - 1 - Question 23
Choose the correctly matched pair.
Detailed Solution for Test: Magnetic Effects of Electric Current - 1 - Question 23
  • Option A: (a) Hans Christian Oersted - Discovered the magnetic effect of electric current in 1820 This is the correct pair. Hans Christian Oersted, in 1820, discovered that a compass needle gets deflected when an electric current passes through a nearby metallic wire, demonstrating the magnetic effect of electric current.
  • Option B: (b) Compass needle - Always points towards the west This is incorrect. A compass needle points towards the north and south directions, not the west.
  • Option C: (c) Iron filings - Represent electric field lines This is incorrect. Iron filings align along magnetic field lines, not electric field lines.
  • Option D: (d) North pole - Repels the south pole of another magnet This is incorrect. The north pole of a magnet attracts the south pole of another magnet, while like poles repel each other.
Test: Magnetic Effects of Electric Current - 1 - Question 24

An electron enters a magnetic field at right angles to it. The direction of force acting on the electron will be _____.

Detailed Solution for Test: Magnetic Effects of Electric Current - 1 - Question 24

The direction of force is perpendicular to the direction of the magnetic field and current, as given by Fleming's left-hand rule. Since the electron enters the magnetic field at right angles to it, the force is directed into the page.

Test: Magnetic Effects of Electric Current - 1 - Question 25

What is the relationship between the direction of the magnetic field and the direction of the current according to Fleming's left-hand rule?

Detailed Solution for Test: Magnetic Effects of Electric Current - 1 - Question 25
  • According to Fleming's left-hand rule, the relationship between the direction of the magnetic field and the direction of the current is perpendicular. This rule helps determine the direction of motion or the force acting on the conductor by aligning the thumb, forefinger, and middle finger of the left hand in specific orientations.
Test: Magnetic Effects of Electric Current - 1 - Question 26

The magnetic field inside a long straight solenoid-carrying current _____.

Detailed Solution for Test: Magnetic Effects of Electric Current - 1 - Question 26

The magnetic field inside a long straight solenoid carrying current is the same at all points. This characteristic of a solenoid's magnetic field is a key property that remains consistent along its length, providing uniformity in the field distribution.

Test: Magnetic Effects of Electric Current - 1 - Question 27

Which of the following statements about the magnetic effect and the magnetic field are correct?

(i) An electric current through a copper wire produces a magnetic effect.
(ii) Iron filings align themselves along the magnetic field lines of a bar magnet.
(iii) A compass needle always points towards the magnetic north pole.
(iv) The magnetic field is the region surrounding a magnet where the force of the magnet can be detected.

Detailed Solution for Test: Magnetic Effects of Electric Current - 1 - Question 27
  • (i) An electric current through a copper wire produces a magnetic effect. This is demonstrated by the deflection of the compass needle when current flows through the wire.
  • (ii) Iron filings align themselves along the magnetic field lines of a bar magnet, showing the pattern of the magnetic field.
  • (iv) The magnetic field is the region surrounding a magnet where the force of the magnet can be detected. This is evidenced by the iron filings aligning in specific patterns around the magnet.

Statement (iii) is incorrect because a compass needle points towards the geographic north, which is the magnetic south pole of Earth, not necessarily the magnetic north pole.

Test: Magnetic Effects of Electric Current - 1 - Question 28

What do the concentric circles around a straight conducting wire represent?

Detailed Solution for Test: Magnetic Effects of Electric Current - 1 - Question 28
  • The concentric circles around a straight conducting wire represent magnetic field lines.
  • These lines indicate the direction of the magnetic field produced by the electric current flowing through the wire.
  • Understanding the pattern of these field lines is crucial in visualizing the magnetic field's behavior around a current-carrying conductor.
Test: Magnetic Effects of Electric Current - 1 - Question 29

The wire with red insulation cover in the electric supply is called the _____ wire.

Detailed Solution for Test: Magnetic Effects of Electric Current - 1 - Question 29

The wire with red insulation cover in the electric supply is called the live wire. It is also known as the positive wire in the domestic electric circuits.

Test: Magnetic Effects of Electric Current - 1 - Question 30

Choose the correctly matched pair.

Detailed Solution for Test: Magnetic Effects of Electric Current - 1 - Question 30
  • Option A: Magnetic Field Lines - Concentric Circles around a Current-Carrying Wire: Explanation: This is correctly matched. The concentric circles represent the magnetic field lines around a current-carrying straight wire. This pattern is formed when iron filings are sprinkled around the wire, indicating the presence of a magnetic field.
  • Option B: Right-Hand Thumb Rule - Direction of Electric Current - Incorrect: The Right-Hand Thumb Rule is used to determine the direction of the magnetic field around a current-carrying conductor, not the direction of the electric current itself.
  • Option C: Deflection of Compass Needle - Decreases with Increased Current - Incorrect: The deflection of the compass needle actually increases with increased current, indicating a stronger magnetic field.
  • Option D: Magnetic Field Strength - Increases with Distance from Wire - Incorrect: The magnetic field strength decreases as the distance from the current-carrying wire increases.
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