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Electrical Machines Lab Experiments

To verify the law of parallelogram of forces



Aim

To verify the law of parallelogram of forces

Theory:

If two force F1 and F2 acting on a particle, be represented in magnitude and direction by the two adjacent sides of a parallelogram, then their resultant (R) is represented by the diagonal of the parallelogram ,Magnitude and direction of the resultant force is given by:

equation

Apparatus Used:

  1. Board with pulleys
  2. Stepped weights hanger
  3. Strings,
  4. Weights
  5. Drawing Sheets

Procedure:

  1. Take two wire apparatus and fix drawing sheet on the board.
  2. Connect the hanger at the end of each string and hang the giving weight on the pivot provided.
  3. Note down the reading of two weight W1 and W2 &weight R so that equilibrium condition is achieved.
  4. Mark the position of strings on the drawing sheet using mirror after equilibrium condition is reached.
  5. Note down magnitudes of weight F1, F2, R and measure angle ϴ and α.
  6. Repeat the above procedure for various sets of readings. in the table.
  7. Repeat the above procedure for various sets of readings.

Observations and Calculations:

S.no Observed Forces/F1/F2/F3 Observed Angles/θ/α Analytical values/α’/R’ % error R'-R/R'X100 /α’– α/α’X100
1
2
3
4
5

Observations And Calculations : Lami`s Theorem

S.no Observed/Force F1/Force F2/Force F3/ Observed/Angle α/Angle β/Angle γ Analytical/F'1/F'2 % error/F1-F'1/F1X100 / F2-F'2/F2X100
1
2
3
4
5

Result:

  1. Law of Parallelogram of Forces- ________________(Verified /Not verified)
  2. For ____ sets of observations, the observed percentage error is____________________

Precautions:

  1. Pulleys should be smooth.
  2. Place the weights gently
  3. Fix the drawing Sheet properly.

Viva Questions:

Q.-1 What are units of forces? Define force?

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Q.-2.What are the various types of force?

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Q.-3. What do you understand by force?

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Q.-4. What do you understand by the term parallel forces?

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Q.-5. Distinguish between like forces and unlike forces

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Q.-6. What are collinear, coplanar & concurrent forces?

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Q.-7. What is a couple?

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Q.-8. State the characteristics of couple?

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