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Explain how electric and magnetic fields can be used to determine the charge-to-mass ratio of an electron.
Model answer
What a good answer should say
- Electric and magnetic fields can be used to determine the charge-to-mass ratio of an electron by observing the deflection of cathode rays.
- The radius of the circular path of the electron in a magnetic field can be measured, and using the formula q/m = (vB)/(r), where q is charge, m is mass, v is velocity, B is magnetic field strength, and r is radius, the charge-to-mass ratio can be calculated.
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Why this works
This answer is strong as it explains the method of using electric and magnetic fields to measure the charge-to-mass ratio, including the relevant formula. It tests the understanding of the application of fields in experimental physics.
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