**Introduction About Newtons Inverse Square:**

The principle in physics that the effect of certain forces on an object varies by the **inverse square** of the distance between the object and the source of the force. The magnitude of light, sound, and gravity obey this **law**, as do other quantities.watch Introduction About Newtons Inverse Square to learn more.

**Newtons Inverse Square:**

Any point source which spreads its influence equally in all directions without a limit to its range will obey the inverse square law. This comes from strictly geometrical considerations. The intensity of the influence at any given radius r is the source strength divided by the area of the sphere. Being strictly geometric in its origin, the inverse square law applies to diverse phenomena. Point sources of gravitational force, electric field, light, sound or radiation obey the inverse square law. It is a subject of continuing debate with a source such as a skunk on top of a flag pole;

**Applications of the inverse square law:**

Gravity ,Electric field Light Sound RadiationIn radiographic inspection, the radiation spreads out as it travels away from the gamma or X-ray source. Therefore, the intensity of the radiation follows Newton’s Inverse Square Law. As shown in the image to the right, this law accounts for the fact that the intensity of radiation becomes weaker as it spreads out from the source since the same about of radiation becomes spread over a larger area. The intensity is inversely proportional to the distance from the source.

In industrial radiography, the intensity at one distance is typically known and it is necessary to calculate the intensity at a second distance. Therefore, the equation takes on the form of:

Where:

I1 = Intensity 1 at D1

I2 = Intensity 2 at D2

D1 = Distance 1 from source

D2 = Distance 2 from source

Note: This is the commonly found form of the equation. However, for some it is easier to remember that the intensity time the distance squared at one location is equal to the intensity time the distance squared at another location. The equation in this form is:

I1 x d12 = I2 x d22

Useful for CBSE, ICSE, NCERT & International Students

Grade :9

Subject : Physics

Lesson : Gravitation

Topic:Newtons Inverse Square

Visit www.oztern.com to find personalized test preparation solutions for Pre Medical – AIPMT, AIIMS, JIPMER, State, Pre Engineering – IIT JEE, JEE MAIN, BITSAT, State and Foundations – Class 6 to 10