The figure shows a velocity selector that can be used to measure the speed of a

Question

The figure shows a velocity selector that can be used to measure the speed of a charged particle. A beam of particles is directed along the axis of the instrument. A parallel plate capacitor sets up an electric field E, which is oriented perpendicular to a uniform magnetic field B. If the plates are separated by 2.0 mm and the value of the magnetic field is 0.60 T, what voltage between the plates will allow particles of speed 5.0 times 10^5 m/s to pass straight through without deflection? 190 V 600 V 3800 V 94 V 1900 V As shown in the figure, a small particle of charge q = -7.0 times 10^-6 C and mass m = 3.1 times 10^-12 kg has velocity v_0 = 9.4 times 10^3 kg as it enters a region of uniform magnetic field. The particle is observed to travel in the semicircular path shown, with radius R = 5.0 cm. Calculate the magnitude and direction of the magnetic field in the region.

Explanation / Answer

20. for no delflection,

Fnet = electric force - magnetic force = 0

qE - qvB = 0

E = v B = 5.0 x 10^5 x 0.60 = 3 x 10^5 V/m

and V = E.d = (3 x 10^5) (2 x 10^-3) = 600 Volt

Ans(E)

21.

q v B = m v^2 / R

B = m v / q R = (3.1 x 10^-12 x 9.4 x 10^3) / (7 x 10^-6 x 0.05)

B = 0.083 T

direction = into the page.

Related Questions

Navigate

• Browse (All)
• Browse T
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.