Final answer:
Colloidal particles can be demonstrated to be electrically charged through methods such as electrophoresis and observing Brownian motion. These techniques provide evidence of the electrical charges present on the particles.
Step-by-step explanation:
Colloidal particles can be demonstrated to be electrically charged through various methods. One such method is by conducting an electrophoresis experiment. In electrophoresis, colloidal particles are placed in an electrolytic cell and subjected to an electric field. The particles will move towards the electrode that carries a charge opposite to their own charge, which demonstrates that they are electrically charged.
Another method to demonstrate the electric charge of colloidal particles is by observing their Brownian motion. Brownian motion is the rapid and random movement of colloidal particles due to collisions with molecules of the dispersion medium. This motion is caused by the thermal motions of fluid molecules colliding with the particles, and it provides indirect evidence of the electrical charges on the particles.
Overall, measuring the size or color of colloidal particles alone cannot directly demonstrate their electric charge. Instead, electrophoresis experiments and observations of Brownian motion are more reliable methods to confirm the electrical charges on colloidal particles.