भारतीय रसायन के पिता आचार्य प्रफुल्ल चंद्र रे की जयंती पर व्याख्यान का आयोजन विज्ञान भारती उदयपुर इकाई एवं बीएन कॉलेज ऑफ फार्मेसी, बीएन विश्वविद्यालय के संयुक्त तत्वावधान में कार्यक्रम सम्पन्न उदयपुर, 2 अगस्त। भारतीय रसायन के पिता आचार्य प्रफुल्ल चंद्र रे की जयंती के अवसर पर विज्ञान भारती उदयपुर इकाई (चित्तौड़ प्रांत) एवं बीएन कॉलेज ऑफ फार्मेसी, बीएन विश्वविद्यालय के संयुक्त तत्वावधान में एक विशेष व्याख्यान का आयोजन किया गया। कार्यक्रम का उद्देश्य आचार्य पी.सी. रे के वैज्ञानिक योगदान एवं उनके देशभक्ति से ओतप्रोत जीवन पर प्रकाश डालना था। ज्ञातव्य है कि भारत की पहली फार्मा कंपनी आचार्य रे ने ही बंगाल केमिकल एंड फार्मास्यूटिकल्स लिमिटेड, कोलकाता में 1901 में प्रारंभ की थी। कार्यक्रम में विज्ञान भारती के उद्देश्य एवं गतिविधियों की जानकारी डॉ. अमित गुप्ता द्वारा दी गई। आचार्य पी.सी. रे के जीवन और कार्यों पर मुख्य व्याख्यान डॉ. लोकेश अग्रवाल द्वारा प्रस्तुत किया गया। उन्होंने बताया कि कैसे आचार्य रे ने विज्ञान को समाज की सेवा का माध्यम बनाया और रसायन विज्ञान में भारत को आत्मनिर्भर बनान...
Thomson’s parabola method
Positive ray analysis
- This method is used to find the charge to mass ratio.
Thomson parabola method
- T = Discharge tube, the pressure of gas in this tube is kept 0.01 mm of Hg
- E = Capillary tube
- C = Cathode, which is perforated with an extremely small holes
- W = Water jacket, used to cool the cathode
- A and B = Metallic plates, the electric field is applied between these plates
- N and S = North and south poles of a heavy magnet
- K = Highly evacuated camera
- P = Photographic plate
- R = Liquid air trap, used to keep the pressure in K quite low
Working
- To ensure the supply of the gas, a steady steam of the gas is allowed to pass through E and after circulating the tube, it is escaped through M.
- The positive ion produced in T move towards C.
- The ion which reaches C axially. pass through its fine hole in the form of narrow beam.
- After crossing C, the parallel beam of ions enters into the electric and magnetic field.
- The electric field is perpendicular to the direction of ions.
- After it the beam enters into K and finally it is received on P.
- When the photographic plate P is exposed, we get a series of parabolas.
Theory
- Let m, q and v are mass, charge and velocity of positive ions respectively.
- When no field is applied, then these ions will strike at point O.
- Here O is undeflected spot.
Action of electric field (E)
- Let l = length of path of positive ions over which the electric field is applied.
- Force on particle due to electric field E, Fe = qE
- Now, acceleration on particle, a = qE / m
- Time taken by particle to cross electric field, t = l / v
- Since u = 0, and a = qE / m, therefore
- Displacement of particle
- After crossing E, the ion moves in a straight line, and strikes at a point on photographic plate, which is at a distance x from O
Action of magnetic field (B)
- Let the magnetic field B is applied in the same direction as E and over the same length l.
- Due to magnetic field, the positive ions will deflect, but their deflection will be at right angle to the deflection of ions due to electric field.
- Let due to B, the positive ions strikes the plate at a distance y from O, and OY ⊥ OX.
∵ a՛ = Fm / m
∴ a՛ = qvB / m
- Displacement
Action of combined electric (E) and magnetic field (B)
- For it we eliminate v from x and y.
- If E and B are kept at a constant value, and if q/m is constant, then
- This is equation of parabola. It means the motion of a charged particle in electromagnetic field will be parabolic in nature.
- Since the equation of y2 / x is independent of v, so the particle of same q/m, but of different v will fall on the different points of same parabola.
- The position of any individual particle will depend on v.
- The entire parabola is a velocity dispersion or a velocity spectrum.
- Since this equation depends on q/m, so the ions of different q/m will lie along the different parabola.
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