The yield is the effective interest rate on bonds. The yield will vary inversely with the market price of the Bond.
Yield= (Coupon/ Market Price of Bond) X 100

Interest payouts on bonds are fixed; an increase in bond price means you (or buyer) pay more for the same returns, so effective returns are less. Another way is also true: if bond prices decrease, you (or buyer) are paying less for the same returns; hence effective returns are more. Thus bond yield and bond price are inversely related.