Original Question: A central bank raises interest rates on reserves
Answer: Investors are less likely to purchase bonds:
Reason: When the economy is good, the level of borrowing money becomes extraordinarily high since there is confidence in the market.
As in, people believe that they can return the money back to the bank since there is a high chance of making the money back up again at a profit.
However, as more and more people do that, the economy heads into state of inflation.
To ensure that the inflation rate doesn't go up sky-high, central banks raise the interest rate on loans which discourages investors to get loans or bonds due to how much they need to pay back later on.
Hope that helps!