Final answer:
The metal bar will have a negative charge as a result of being charged by a positively charged glass rod through the process of induction, where charge separation occurs without direct contact.
Step-by-step explanation:
When a positively charged glass rod is used to charge a metal bar by induction, the charge on the metal bar will be negative. In this process, the glass rod is brought near but does not touch the metal bar. The presence of the positively charged rod repels the electrons in the metal bar, causing them to move away from the rod and accumulate on the far side, leaving the near side positively charged.
If the bar is then grounded on the far side, electrons will flow into the bar to neutralize the positive charge. When the connection to the ground is removed and then the glass rod is taken away, the metal bar is left with an excess of electrons and thus has a negative charge. This separation and redistribution of charge occurs without direct contact between the charged rod and the metal bar, demonstrating the principle of charging by induction.