Final answer:
The charge on a 1.20 mm diameter ball bearing with 1.50×109 excess electrons is -2.40×10-10 C, which indicates it is negatively charged.
Step-by-step explanation:
To find the charge on a 1.20 mm diameter ball bearing with 1.50×109 excess electrons, we need to use the elementary charge of an electron, which is approximately -1.60×10-19 C (coulombs). Multiplying the number of excess electrons by the charge per electron gives us the total charge on the ball bearing:
Total charge = number of excess electrons × charge per electron
Total charge = 1.50×109 × (-1.60×10-19 C/electron)
Total charge = -2.40×10-10 C
The negative sign indicates that the ball bearing has an excess of electrons, making it negatively charged.