Question

after focusing on an object with the low power objective lens, you are trying to bring it into focus under the 40x objective lens, but the field of view is very dark. which of the following may remedy this problem?
multiple choice
add more immersion oil
only use lower power magnification.
adjust the fine adjustment knob.
increase the light intensity

Explanation:

The problem is about using a microscope. A dark field of view when using the 40x objective (high power) can be remedied by increasing light intensity, as more light will make the view brighter. Adding immersion oil is for 100x oil immersion objective, using lower power doesn't solve the darkness at 40x, and fine adjustment knob is for focus, not brightness.

Answer:

D. Increase the light intensity