Solution:

To find the drift velocity $v_d$ of the electrons, we use the formula for current in terms of drift velocity:

$$I = n A e v_d$$

Where:

• $I$ is the current (1.2 A),
• $n$ is the number of free electrons per unit volume ($5 \times 10^{28} \, \text{m}^{-3}$),
• $A$ is the cross-sectional area of the conductor ($10^{-4} \, \text{m}^2$),
• $e$ is the charge of an electron ($1.6 \times 10^{-19} \, \text{C}$),
• $v_d$ is the drift velocity of the electrons (which we need to calculate).

Step 1: Rearranging the formula to solve for $v_d$

$$v_d = \frac{I}{n A e}$$

Step 2: Substituting the given values

$$v_d = \frac{1.2}{(5 \times 10^{28}) \times (10^{-4}) \times (1.6 \times 10^{-19})}$$

Step 3: Performing the calculation

$$v_d = \frac{1.2}{(5 \times 10^{28}) \times (10^{-4}) \times (1.6 \times 10^{-19})}$$ $$v_d = \frac{1.2}{8 \times 10^{6}}$$ $$v_d = 1.5 \times 10^{-7} \, \text{m/s}$$

Final Answer:

The drift velocity of the electrons is $\boxed{1.5 \times 10^{-7} \, \text{m/s}}$.