Low power to catch a drop to 980 hours

A lab tests $H_0: \mu = 1000$ against $H_1: \mu \neq 1000$ for bulb life, with a known $\sigma = 50$, a sample of $n = 25$, at the two-sided 5% level. Suppose the true mean life is actually $\mu = 980$.

Find the power of the test (the probability it correctly rejects $H_0$).