Answer:
First, the image moves in and out of focus too quickly, so that it is difficult to precisely adjust the focus. Second, you run the risk of crashing the objective into the slide. Use the coarse focus only with the 4x low power objective. You can use the fine focus knob with all objectives.
Explanation:
You haven't said whether the two resistors are connected
in series or in parallel. It makes a difference.
-- If they are in series, then their combined effective resistance is
(3 + 2) = 5 ohms.
Current in the circuit is (voltage)/(resistance) = 1.5/5 = 0.3 Amp.
-- If they are in parallel, then their combined effective resistance is
(3 x 2) / (3 + 2) = (6/5) = 1.2 ohms.
Current in the circuit is (voltage)/(resistance) = 1.5/1.2 = 1.25 Amp.
Answer:

Explanation:
Given

Required
Rewrite using scientific notation
The format of a number in scientific notation is

Where 
So the given parameter can be rewritten as

Express as a power of 10

Hence, the equivalent of the mass of the sun in scientific notation is:

So we want to know how can we detect infrared rays without an instrument. Infrared rays or heat, are a part of electromagnetic spectrum. We have specialized nerve cells in our skin called thermoreceptors that can detect differences in temperature that are produced by infrared part of EM spectrum.