Can you write on this causing a magnetic image to appear if you attached a small neodymium magnet to the end of dried up pen?

Only if you have a small enough magnet, otherwise the characters would be so large you could only write one word.After reading "Sadly, no." I tried with a small motor magnet and was able to produce "123" and "Hi" that were legible from the front.Not sure if that is useful for you.

Will this show the tracks on magnetic audio tape?

Not usefully. It might just show some magnetic field on a cleverly recorded tape (eg: Like a lightning flash recorder), but neither the resolution nor the contrast would show normal audio tracks. That is simply not it's function.

ASIN	B005HYCM8M
Best Sellers Rank	#21,069 in Toys & Games ( See Top 100 in Toys & Games ) #1,730 in School Supplies
Brand	Master Magnetics
Colour	Blue
Customer Reviews	4.1 out of 5 stars 193 Reviews
Enclosure Material	Plastic
Global Trade Identification Number	00095421005635
Item Type Name	magnetic
Manufacturer	0
Material	Plastic
Shape	Rectangular
Size	2.5 x 4 inch
UPC	095421005635
Unit Count	1.0 Count

Magnet Source Magnetic Field Viewer Card (Pack of 1)

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