To perform the subtraction \( 4.8 \times 10^{-3} - 9.4 \times 10^{-6} \), we first need to express both numbers with the same exponent.
We can convert \( 4.8 \times 10^{-3} \) into base \( 10^{-6} \):
\[ 4.8 \times 10^{-3} = 4.8 \times 10^{-3} \times \frac{10^3}{10^3} = 4.8 \times 1000 \times 10^{-6} = 4800 \times 10^{-6} \]
Now we can perform the subtraction:
\[ 4800 \times 10^{-6} - 9.4 \times 10^{-6} = (4800 - 9.4) \times 10^{-6} = 4790.6 \times 10^{-6} \]
Next, we need to express \( 4790.6 \) in scientific notation. We can rewrite it as:
\[ 4790.6 = 4.7906 \times 10^3 \]
Thus,
\[ 4790.6 \times 10^{-6} = 4.7906 \times 10^{3} \times 10^{-6} = 4.7906 \times 10^{-3} \]
Rounding \( 4.7906 \) to two decimal places, we get \( 4.79 \).
Therefore, the final answer in scientific notation is:
\[ \boxed{4.79 \times 10^{-3}} \]