# Repulsive force with varying distance Using Magnets

For the report, we suggest the following headings (I) Abstract, (II) Introduction, (III) Experimental Method, (IV) Results and Discussion, (V) Conclusion, with no strict word limit (although communication is a marking criteria, and being concise is important).

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Establishing  the function of  repulsive force between two magnets with variation in distance.

Abstract :

The objective of this lab report is to establish experimentally the repulsive force between two magnets as a function of distance between magnets. It describes a simple experimental set up to calculate repulsive force with varying distance. It also describe linearization a power function using logarithms.

Introduction :

A permanent magnet is a magnetic dipole. The north pole align itself to the north pole of the earth and south pole of the magnet align itself to the south pole of the earth. There is attractive force between opposite poles of two magnet and repulsive force between similar magnetic poles.

Procedure :

This exercise requires a digital weighing scale , two magnets and other equipments as shown in the Fig.1

Fig.1 Measuring repulsive force between two magnetic poles with varying distance.

One magnet was fixed in a vertical position which was varied while performing experiment.And other magnet was placed verically on a digital weighing scale. The Weighing machine indicated the repulsive force between two magnetic pole.

The distance between the centres of the magnets was varied by sliding the clamp on the stand and was measured using a vernier calliper. And repulsive force was measured for each distance from the reading of weighing machine.

Observation table

 Data point X-axis  (Distance  r)(CM) Y-Axis (Force)(N) 1 4.7 8.3 2 4.5 8.3*2 3 4 8.3*3 4 3.7 8.3*4 5 3.5 8.3*5 6 3.3 8.3*6 7 3.2 8.3*7 8 3.0 8.3*8 9 2.9 8.3*9 10 2.7 8.3*10 11 2.7 8.3*11 12 2.6 8.3*12 13 2.5 8.3*13 14 2.4 8.3*14 15 2.3 8.3*15 16 2.25 8.3*16 17 2.1 8.3*17 18 2.1 8.3*18 19 2 8.3*19 20 2 8.3*20 21 1.95 8.3*21 22 1.95 8.3*22 23 1.9 8.3*23 24 1.9 8.3*24 25 1.9 8.3*25 26 1.85 8.3*26

Result and discussion :

After plotting the  data collected from the experiment , it was observed that repulsive force between magnet poles varied proportionally with 1/r.Where n was between 1 and 2.

The graph was in the form of power law as shown in the equation where 'a' is a constant and n is an exponent.

F(r) = arn

In order to linearise the function we take the Log of both side of the equation 1 which becomes

log(F) = log(a) + log(r)

A plot log(F) vs log(r) is shown in figure 2.

Conclusion :

This experiment requires a simple equipments but demands attention to avoid experimental errors. It was found that repulsive force between two magnet depends on 1/r

proportionally. Where 'r' is the distance between the magnets and 'n' was between 1 and 2. It should remarked that result of this experiment depends heavily on the types of magnets and the geometry of the magnets.