Adevice made by j. j. thomson to process and detect electrons is the: magnetron geiger counter cathode-ray tube vacuum tube

I think you forgot to add the options but based on my research the correct answer is "cathode-ray tube." This is the device made by J. J. Thomson to process and detect electrons is the: magnetron Geiger counter cathode-ray tube vacuum tube. Thank you for posting your question. I hope that this answer helped you. Let me know if you need more help. 

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