Experiment No. 2 bsc.5th semester
Object
To determine the wavelength of laser beam using plane
diffraction grating .
Apparatus
Diode laser with power supply (λ = 670 nm) visible red region spectrometer circular
table but without collimator and telescope , instead two holders are provided ,
one for holding the laser source and other for laser detector diffraction
grating (usual 1500 λπ)
nanometer to measure the cutout current spirit level e t c .
Formula
(a + b) sin θ = nλ
Wavelength λ = ( a + b) sin θ/n
. n = order of spectra (n = 1
, e t c)
θ = angle of diffraction for order n.
Observation Table
N
= 1500 L .P . I
|
V₁ |
V₂ |
V₁
+ V₂/2=d |
D |
θ |
|
4.75 |
4 |
4.37 |
12.5 |
19.2696 |
|
4.5 |
3.25 |
3.77 |
10 |
20.65 |
Calculation
. nλ = sin l /N
. n = 1
.λ = sin 19.2696x2.54/1500 cm
λ₁ = 5585 Aͦ
λ₂ = sin 20.65 x 2.54/1500
λ₂ = 5971 Aͦ
λ = λ₁
+ λ₂/2
5585 + 5971/2
11556/2
Λ = 5778 Aͦ ans
Result
To value of wavelength of the laser beam is found to be
57.78 Aͦ
Sources of Error and precaution
- Laser beam should not be locked at directly. It is hazardous to the eyes.
- 2. Even looking at
the secular reflections from smooth surface should be avoided.
- 3. The laser is to
be switched off after nothing observations or when not required.
- 4. The laser and is power supply should never be tampered with when it is in ‘ON’ condition , the current is of the order of 10 mA at 2 kv.
- 5. Laser experiments are to be performed only in the presence of the teacher.
Note
(Please note: if a particular experiment is not visible, please search for it using the search box—for example, Experiment No. 3 To determine the refractive index of the material of a prism using sodium light.
कृपया ध्यान दीजिये अगला एक्सपेरिमेंट न दिख रहा हो वो आप सर्च बॉक्स में सर्च कर लीजिये . जैसे , एक्साप्रिमेंट नंबर. 3 या फिर To determine the refractive index of the material of a prism using sodium light.
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