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# Tag Archives: r2

## Form of Kepler’s in a different universe!

Mukta asked:

“imagine a planetary system in which gravitational force varied as 1/r instead of 1/r^{2} .what relation would correspond to KEPLER’S THIRD LAW (SQUARE OF TIME PERIOD / CUBE OF SEMI MAJOR AXIS.?”

**(Answer)**

If the gravitational force varied as 1/r instead of 1/r^{2} , then Kepler’s Law of periods would have to be modified accordingly and it would give T proportional to r.

## Wire Gauge and Resistance problem

I am using 18 **gauge** nicrome wire having ohm of 17.3 , 220 volt. I want to use 10 gauge wire how to decide the length?

Padmanava asked

**Answer**:

18 gauge corresponds to a diameter of 1.22 mm

Therefore radius **r1**= 1.22/2=0.61 mm=**0.00061m**

10 gauge meansĀ diameterĀ is 3.25 mm

Radius **r2** = 3.25/2=1.625mm=**0.001625m**

Sine the resistance needs to be the same, we can use the formula

Which gives

As resistivity is same.

Substitute the values and you will get the answer.