J. J. Thomson is best known for his discoveries about the nature of cathode rays
ID: 1260953 • Letter: J
Question
J. J. Thomson is best known for his discoveries about the nature of cathode rays. His other important contribution was the invention, together with one of his students, of the mass spectrometer, a device that measures the ratio of mass m to (positive) charge qof an ion.
The spectrometer consists of two regions as shown in the figure.(Figure 1) In the first region an electric field accelerates the ion and in the second the ion follows a circular arc in a magnetic field. The radius of curvature of the arc can be measured and then the m/q ratio can be found.
Part A
After being accelerated to a speed of 1.76105m/s , the particle enters a uniform magnetic field of strength 0.900T and travels in a circle of radius 35.0cm (determined by observing where it hits the screen as shown in the figure). The results of this experiment allow one to find m/q.
Find the ratio m/q for this particle.
Express your answer numerically in kilograms per coulomb.
J. J. Thomson is best known for his discoveries about the nature of cathode rays. His other important contribution was the invention, together with one of his students, of the mass spectrometer, a device that measures the ratio of mass m to (positive) charge qof an ion. The spectrometer consists of two regions as shown in the figure.(Figure 1) In the first region an electric field accelerates the ion and in the second the ion follows a circular arc in a magnetic field. The radius of curvature of the arc can be measured and then the m/q ratio can be found. Part A After being accelerated to a speed of 1.76x 10^5m/s , the particle enters a uniform magnetic field of strength 0.900T and travels in a circle of radius 35.0cm (determined by observing where it hits the screen as shown in the figure). The results of this experiment allow one to find m/q. Find the ratio m/q for this particle. Express your answer numerically in kilograms per coulomb.Explanation / Answer
R = (m*v) / (q*B)
R = radius of circular motion
m = mass of charge
v = velocity of charge partical
B = magnetic field
q = charge
(m/q) = (R*B)/v
(m/q) = 35*10^(-2) * 0.9 / 1.76*10^(5)
(m/q) = 17.8977 *10^(-7) kg/C
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