An object moves in a circle at constant speed. State the names of two quantities that change as the motion continues.
A charged particle of mass $m$ and charge $q$ enters a region of uniform magnetic field at right angles to the field lines. The magnetic flux density is $B$. The particle travels in a circle with period $T$ and radius $r$. By considering the magnetic force acting on the particle, show that $B = \frac{2\pi m}{qT}$.
The particle is an alpha particle. Its period of circular motion is $2.5\,\mu\text{s}$. Calculate $B$.
A second alpha particle is in the same uniform field. It travels in a circle of radius $2r$. State and explain how the periods of the two particles compare.
The speed of the alpha particle in (b)(ii) is $1.1 \times 10^{6}\,\text{m s}^{-1}$. An electric field is applied so that this particle now moves with constant velocity. Use your answer in (b)(ii) to calculate the electric field strength $E$. Give the unit with your answer.
The speed of the alpha particle in (b)(ii) is $1.1 \times 10^{6}\,\text{m s}^{-1}$. An electric field is applied so that this particle now moves with constant velocity. Use your answer in (b)(ii) to calculate the electric field strength $E$. Give the unit with your answer.