To evaluate the expression \(1.9 \times 10^3 - 1.6 \times 10^3\), we can first factor out \(10^3\):
\[ 1.9 \times 10^3 - 1.6 \times 10^3 = (1.9 - 1.6) \times 10^3 \]
Now, we can perform the subtraction:
\[ 1.9 - 1.6 = 0.3 \]
Now, we substitute this result back into the expression:
\[ 0.3 \times 10^3 \]
Next, we express this in scientific notation. We can rewrite \(0.3\) as \(3.0 \times 10^{-1}\):
\[ 0.3 \times 10^3 = (3.0 \times 10^{-1}) \times 10^3 \]
When multiplying the powers of 10, we add the exponents:
\[ 3.0 \times 10^{-1 + 3} = 3.0 \times 10^2 \]
Thus, the final answer in scientific notation is:
\[ \boxed{3.0 \times 10^2} \]