PART A)
Equivalent resistance in parallel is given as

now we have


PART B)
since potential difference across all resistance will remain same as all are in parallel
so here we can use ohm's law

for 4 ohm resistance we have


PART C)
since potential difference across all resistance will remain same as all are in parallel
so here we can use ohm's law

for 8 ohm resistance we have


Yes A diamond* is a pure substance
The problem statement is simply asking us to convert units. We convert from units of ft^3 to units of m^3. To do this, we need a conversion factor. For this case, we use 1 m is equal to 3.28084 ft. We do as follows:
5.0 ft^3 ( 1 m / 3.28084 ft )^3 = 0.1416 m^3
Answer:

Explanation:
According to the newton's second law of motion we can apply F=ma hear
Force = mass * acceleration
(assume the piano is moving left side )
←F = ma

We get the clearest image if there is no magnification. When we have no magnification the image and real object have the same size.
If we look at the diagram that I attached we can see that:

Two triangles that I marked are similar and from this we get:

The image and the object must have the same height so we get:

This tells how far the screen should be from the lens.
The position of the screen on the optical bench is: