OK, so you've brought up 3 very interesting topics, actually.
1. Why do coins have ridges?
This is known as "reeding". So, basically, back in the day, when coins were actually made from precious metals like gold & silver & their value depended on their actual weight, people quickly discovered you could make money by shaving or clipping tiny bits off coins & then using those little bits to make new coins. It was a big problem in the ancient world, apparently.
Cut or shave tiny bits off the coin & no one notices. 👀 Then use the shavings to melt into new coins. But this goes WAY BACK. To ancient Persia, Greece & the Roman Empire. It wasn't just Jews doing it. It was widespread. Cunning people everywhere will find ways to make money. That's capitalism for ya. Nature, uh, finds a way, lol.
It became a big problem actually as it devalued coins & apparently some coins ended up losing 30% of their actual weight & caused serious economic problems. Penalties for coin clipping were apparently very severe (like death penalty or exile).
So eventually Europe introduced this thing called "reeding" in the 17th C, which is where you add little grooves on the edge of coins. And then it's obvious if someone has been shaving bits off because you can clearly see if the grooves are missing. So that's why coins have those little grooves to this day. Although nowadays it's more a tradition since we don't use precious metals to make coins & their value is not based on the weight of the actual metal anyway.
2. >Why have the jews been expelled from multiple European nations?
Well, that's a VERY big topic & not something we can answer in a simple social media comment thread. I'm not really qualified to either. I'm not even Jewish or an academic. Plenty of stuff has been written about it though. Although I genuinely wish I could. But we could be here for months.
3. >Why are all the heads of Federal Reserve jewish?
Are they though?
Charles S Hamlin (1914–1916) – ❌
William PG Harding (1916–1920) – ❌
Daniel R Crissinger (1923–1927) – ❌
Roy A Young (1927–1930) – ❌
Eugene Meyer Jr. (1930–1933) – ❌
Eugene R Black (1933–1934) – ❌
Marriner S Eccles (1934–1948) – ❌
Thomas B McCabe (1948–1951) – ❌
William McChesney Martin Jr. (1951–1970) – ❌
Arthur F Burns (1970–1978) – ❌
G William Miller (1978–1979) – ❌
Paul Volcker (1979–1987) – ❌
Alan Greenspan (1987–2006) – Jewish ✅
Ben Bernanke (2006–2014) – Jewish ✅
Janet Yellen (2014–2018) – Jewish ✅
Jerome Powell (2018–now) – ❌