Question

J Question 5 5 pts A proton and an alpha particle (the nucleus of a helium atom, containing two protons and two neutrons) traveling at the speed enter a uniform magnetic field. The velocity vector of each particle is perpendicular to the magnetic field. What is the ratio of the radii of their circular orbits (r proton/ alpha)? O 0.5 O 1.0 O 1.5 O 2.0 O 4.0 Question 6 5 pts A horizontal length of current-carrying wire is suspended from two identical flexible leads that are under tension due to the weight of the wire. The wire is oriented at right angles to a uniform magnetic field that has a magnitude of 4.5 T and is directed out of the screen of the figure. The length L of the wire is 5 cm and its mass m is 10 g. What current will produce a magnetic force on the wire such that it doubles the tension in the flexible leads, and which way is the current flowing through the wire? Current-carrying wire suspended from identical flexible leads WBO magnetic field (out of the screen) Ceiling I, current-carrying wire L O 0.33 A, current flows left to right O 0.33 A, current flows right to left O 0.44 A, current flows left to right O 0.44 A, current flows right to left O 0.67 A, current flows left to right

Answer 1

5)

magnetic force= centripetal force

qvB = mv^2/r

r = mv/qB

since v,B are same , they would not have any effect on the ratio

r(proton) / r(alpha) = (m(proton) / m(alpha)) *( q(alpha) / q(proton))    [ m(alpha) = 4m(proton) and q(alpha)= 2q(proton))

r(proton) / r(alpha) = (1/4) *2 = 1/2

= 0.5