Question

1. John observed bacteria at 100X under the oil immersion and then decided to go back to 40X

Answer 1

Answer:

See the answer below

Explanation:

In the first instance, the 100X objective does not have any business touching the slide on the stage so that there would not be any reason to raise it a little in order to go back to a lower objective. At higher objectives, only the fine adjustment should be used to bring the object into focus so as to avoid the objective lens from touching the slide which can damage the objective and or break the slide on the stage.

For the X100 objective to be raised in order to avoid a damage to it, it means John allowed the objective to come too close to the slide in the first place. This should not have been so.