Question

Several magnetic and non-magnetic bars of equal dimensions are glued together as shown on the left. If blue denotes magnetic north, red denotes magnetic south and grey denotes non-magnetic material, what will be the configuration of the faces on the other end?

• A. Fig A
• B. Fig B
• C. Fig C
• D. Fig D

Hint:

Always remember that when you walk to the opposite side of an object to view its back, your left and right are swapped. This horizontal reflection is key to matching the wings of the assembly correctly.

Answer 1

The Correct Option is C

Step 1: Understanding the Question:
This question belongs to the topic of

3D Spatial Projection and Magnetic Polarity.
We are given a 3D assembly of glued bar magnets (Blue = North, Red = South) and non-magnetic bars (Grey). We need to determine the color configuration of the faces on the opposite end of the assembly when viewed directly.

Step 2: Key Formula or Approach:
We apply the physical and spatial laws of bar magnets:

• A single bar magnet has opposite poles at its two ends. Therefore, a Blue (North) front face must have a Red (South) back face, and a Red front face must have a Blue back face.

• Non-magnetic bars (Grey) are uniform throughout and remain Grey at both ends.

• When looking directly at the back face from the other end, the left and right positions are horizontally mirrored relative to the front face.


Step 3: Detailed Explanation:

• Let us map the front face configuration:
- Top-center: Blue (North) \(\to\) opposite end must be Red (South).
- Middle-center: Red (South) \(\to\) opposite end must be Blue (North).
- 3rd-center: Grey (Non-magnetic) \(\to\) opposite end must be Grey.
- Bottom-center: Blue (North) \(\to\) opposite end must be Red (South).
- Left-wing: Grey (Non-magnetic) \(\to\) viewed from the back, this bar is on the right side, so the right-wing must be Grey.
- Right-wing: Blue (North) \(\to\) viewed from the back, this bar is on the left side, and its opposite end must be Red (South).

• Let us assemble the direct back-view configuration from top to bottom:
- Central column: Red (top), Blue (second), Grey (third), Red (bottom).
- Left-wing: Red.
- Right-wing: Grey.

• Let us match this with the options:
- Option C: Displays exactly this layout: a Red top-center and left-wing, a Blue middle-center, and a Grey right-wing and third-center. This matches our physical and geometric deduction perfectly.


Step 4: Final Answer:
Option (C) is the correct configuration on the other end.