Module ІІІ. Physics of oscillations and waves. optics

LABORATORY WORK

STUDY of STATIONARY WAVES PROPERTIES.

DETERMINATION of FREQUENCY of STRING OSCILLATIONS

Task 1. To measure proper frequency of oscillations

1.1. Set string tension Р₁, to measure the oscillation frequency of strings three times in which the string entered in one, two and four half wavelength. Enter the results into table 1.

Table 1

1.2. Set string tension Р₂, to measure the oscillation frequency of strings three times in which the string entered in one, two and four half wavelength. Enter the results into table 1.

1.3. Set string tension Р₃, to measure the oscillation frequency of string three times in which the string entered in one, two and four half wavelength. Enter the results into table 1.

1.4. Write down characteristics of string:

diameter d = _________m;, length l = _________m; cooper density =______________kg/m³

1.5. Calculate theoretical value of string oscillations frequency according to the formula:

f_{th і} = .

1.5. Compare the experimental and theoretical values of frequency.

Task 2. Calculate the errors of measurements of frequency f₁.

- Determine mean arithmetic value f_1ave.

where n =3 the quantity of measurements. Enter the results into table 1.

- Calculate deviation from average value:

- Calculate root-mean-square deviation for average value

- Get absolute error of measuring average value multiplying the value on the Student’s coefficient for reliable probability and number of experiments n = 3,:

.

- Fractional error of measurements average value of wavelength of supersonic wave:

% .

- Write results of measurements in such a way

=_________Hz.

Task 3. Determination of wave phase velocity

3.1. Calculate experimental value of wave phase velocity for each mean value of frequency according to the formula

.

Table 2

3.2. Calculate theoretical value of wave phase velocity according to the formula

υ_{th i} = .

Enter the results into table 1.2.

3.3. Compare the experimental and theoretical values of wave phase velocity.

Task 4. Plot the graphs of dependence between wave phase velocity and string tension υ_th= f(P) and on the scaled paper using the data from table 2.

Conclusion:

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The data of laboratory work fulfilment _______________________________________________

Pass mark ________________________________________ Signature ______________________

Mark of laboratory work defence __________________ Signature _______________________

questions to be admitted for doing laboratory work
and its defending

1. What is the stationary wave?

2. Conditions for stationary wave creation.

3. Deduce the equation of stationary wave.

4. Deduce the equation for coordinates of nodes and antinodes of stationary wave.

5. How is stationary wave represented graphically?

6. Energy of stationary wave.

7. How is frequency of string proper oscillations determined if a sting is fixed on one end; on both ends; in the middle?

8. What is a basic tone and an overtone?

9. Demonstrate how frequency of string proper oscillations and the phase speed of stationary wave depend on string tension.

10. Describe the method of experimental determination of proper frequency of string oscillations.

LABORATORY WORK

Interference of light. Determination of lens curvature radius and light WAVELENGTH USING Newton's rings

Task 1. Determination of Newton’s rings diameters

1.1. Measure points of microscope scale. Enter the results into table 1.

1.2. Calculate the Newton’s rings diameters as microscope scale readings difference. Enter the results into table 1.

Table 1

Exp. No	Ring number, k	Left-hand reading, mm	Right-hand reading, mm	Ring diameter, D, mm	Ring diameter mean value Dave, mm	mm2	, m	e, %

1.3. Determine error of the Newton’s rings diameters measurement. Carry out calculations, for example, for the fourth ring.

— Calculate mean value of diameter of the fourth ring:

— Calculate random deviation of every measured diameter from diameter mean value according to the formula:

— Determine root-mean-square deviations according to the formula:

— Determine the absolute error of diameter measurement according to the formula:

where the Student’s coefficient is t_St = 4,3 (m = 3 and a = 0,95).

— Determine the fractional error of diameter measurement according to the formula:

— Write down the result in the following form:

, m.

Task 2. Calculation of lens curvature radius

2.1. Calculate lens curvature radius according to the formula:

, m.

Enter the results into table 2.

Table 2

Task 3. Determination of the absolute and the fractional errors of lens curvature radius measurement

3.1. Calculate mean value of lens curvature radius according to the formula:

.

Enter the results into table 3.

3.2. Calculate random deviation of every radius from its mean value according to the formula:

Enter the results into table 3.

3.3. Determine root-mean-square deviations according to the formula:

3.4. Determine the absolute error of diameter measurement according to the formula:

where the Student’s coefficient is t_St = 1,83 (m = 15 and a = 0,95).

3.5. Determine the fractional error of lens curvature radius measurement according to the formula:

.

3.6. Write down the result in a form:

, m

Enter the results into table 3.

Table 3

Task 4. Determination of lens curvature radius by graphical method

4.1. Plot graph, putting on axis of ordinates and number of rings on abscissa axis:

4.2. Determine lens curvature radius according to the formula:

4.3. Compare lens curvature radius obtained by analytical and graphical methods. Determine the difference between lens curvature radius determinations according to the formula:

.

Enter the results into table 3.

Task 5. Determination of air clearance thickness

5.1. Determine air clearance thickness between the plano-convex lens and the plane glass plate according to the formula:

Enter the results into table 4.

Task 6. Determination of half-wavelength amount

6.1. Determine the amount of half-wavelength according to formulae:

Enter the results into table 4.

Date: 2015-01-12; view: 1284