1. An unknown charged particle passes without deflection through crossed electric and magnetic fields of strengths 187,500 V/m and 0.1250 T, respectively. The particle passes out of the electric field, but the magnetic field continues, and the particle makes a semicircle of diameter 25.05 cm. Part A. What is the particle's charge-to-mass ratio?

Part B. Can you identify the particle?

a. can't identify

b. proton

c. electron

d. neutron

2. A neutral lithium atom has three electrons. Two of these electrons form an "inner core," but the third-the valence electron-orbits at a much larger radius. From the valence electron's perspective, it is orbiting a spherical ball of charge having net charge +1e (i. e., the three protons in the nucleus and the two inner-core electrons). The energy required to ionize a lithium atom is 5.14 eV. Hint: Consider the energy needed to remove the electron and the force needed to give the electron a circular orbit.

Part A. According to Rutherford's nuclear model of the atom, what is the orbital radius of the valence electron? Express your answer with the appropriate units.

Part B. According to Rutherford's nuclear model of the atom, what is the speed of the valence electron? Express your answer with the appropriate units.