Why are long term bonds sensitive interest rate changes?

Long-term bonds are sensitive to interest rate changes because their fixed interest payments are locked in for an extended period. When interest rates rise, new bonds are issued with higher yields, making existing bonds with lower yields less attractive. This leads to a decrease in the market price of long-term bonds, as investors demand a higher return to compensate for the opportunity cost of holding them. Consequently, the longer the duration of the bond, the greater the price volatility in response to interest rate fluctuations.