Final answer:
The effect of electric current used to detect current flow through a solution with a torch bulb is electrical conductivity. The brightness of the light bulb indicates the solution's ability to conduct electricity, based on the presence and concentration of ions.
Step-by-step explanation:
The effect of electric current that is utilized to detect the flow of current through a solution when a torch bulb is used is electrical conductivity. A conductivity apparatus, often comprising a light bulb or meter, measures the completion of an electrical circuit when the prongs of the apparatus are lowered into an ion-containing solution. If there are enough ions present, such as those in a saline solution or NaCl solution, the ions will carry the current from one prong to the other, closing the circuit and causing the light bulb to light up. This indicates that electrical current is flowing through the solution. Conversely, if the prongs are lowered into a solution with an insufficient number of ions, the light bulb will not light up, reflecting inadequate conductivity. Therefore, the brightness of the bulb is a visual indicator of the solution's ability to conduct electricity.
Additionally, specialized devices like the Coulter counter can detect and count changes in electrical resistance in a saline solution as cells pass through an aperture, indicating current flow. The concentration of ions in a solution significantly affects the amount of electrical current that can pass through, as ions move toward electrodes of opposite charges, completing the circuit and allowing the flow of current to be measured.