Among Sc, Ti, Mn and Co, calculate the spin-only magnetic moment in the oxidation state of the metal having the highest heat of atomisation.
1
4.9 B.M.
2
5.9 B.M.
3
2.9 B.M.
4
3.9 B.M.
Official Solution
Correct Option:
(1)
The magnetic moment is given by: Where is the number of unpaired electrons. For (3d ), . For (3d ), .
For (3d ), . For (3d ), .
Thus, the highest magnetic moment is for , which has .
02
PYQ 2026
medium
physicsID: jee-main
An insulated wire is wound so that it forms a flat coil with turns. The radius of the innermost turn is cm, and of the outermost turn cm. If 20 mA current flows in it then the magnetic moment will be A.m². The value of is ______.
1
4.4
2
2.64
3
3.25
4
1.2
Official Solution
Correct Option:
(2)
Step 1: Understanding the Concept:
For a flat spiral coil, the radius of the turns varies linearly from the inner radius to the outer radius . The magnetic moment of a single loop is . For a spiral, we must integrate the moments of all infinitesimal turns across the radius.
Step 2: Key Formula or Approach:
1. Number of turns per unit radial length .
2. Magnetic moment of a small element : .
3. Total magnetic moment .
Step 3: Detailed Explanation:
1. Substitute the constants:
2. Simplify the expression using :
3. Plug in the values ( ):
4. Converting to : . So, .
Step 4: Final Answer:
The value of is 2.64.
03
PYQ 2026
medium
physicsID: jee-main
Two identical small bar magnets each of dipole moment are placed at a center to center separation of 10 cm, with their axes perpendicular to each other as shown in figure. The value of magnetic field at the point P midway between the magnets is . The value of is _______. ( )
Official Solution
Correct Option:
(1)
Step 1: Understanding the Concept:
The point P is located 5 cm ( ) from the center of each magnet. Relative to one magnet, P is in an axial position. Relative to the other magnet, P is in an equatorial position. The net magnetic field is the vector sum of these two fields.
Step 2: Key Formula or Approach:
1. Axial field: .
2. Equatorial field: .
3. Net field: .
Step 3: Detailed Explanation:
Given and .
Let .
Then and .
The fields are perpendicular, so the net field is:
Substitute :
Comparing with , we get .
Step 4: Final Answer:
The value of is 12.
About Magnetic Moment - JEE-MAIN
Magnetic Moment is a vital chapter for JEE-MAIN aspirants. Mastering the concepts covered in this chapter is essential for securing a top rank.
By rigorously practicing the previous year questions associated with this chapter, you can identify high-yield topics, understand the examiner's perspective, and boost your confidence during the actual exam.
Frequently Asked Questions
Why focus on Magnetic Moment PYQs?
Analyzing PYQs for this specific chapter reveals the most frequently tested concepts and the typical complexity of questions, allowing you to tailor your study plan efficiently.
How to best use this analysis?
Review the topic breakdown to see which sub-topics within Magnetic Moment carry the most weight. Then, tackle the questions iteratively to solidify your understanding.
