Depreciation on computer monitor

Both can be possible. It depends on you what you want. i would advice to charge it as revenue expenditure since not an material figure.

It depends-  whether u have a computer asset a/c created ? then u can add to that account...If u are liable to tax audit..an auditor wud want u to disallow this expense and take depreciation...but as the amount is too small u could possibly debit expense account

write off.. since it does not increse efficiency of the computer on a whole

It all about materiality of the product if this computer cost affect the business then it should be capitalize if it does not then it should not be capitalize .

best advise is capitalize and depreciate because if you charge off to revenue..it could not traceout further periods. if you capitalise it would be easy to track and asset monitoring and asset utilization analysis.