[填空题]
A proton follows a spiral path throug ife)pjec .pu,*l .qe*tl byc. h9i-m)+ ihr si+5u *edd-vd*eeqx+rw bu1f6/h a gas in a magnetic field of 0.010 T, perpendicular to the plane of the spiral, as shown in (Fig. Below). In two successive loops, at points P and Q, the radii are 10.0 mm and 8.5 mm, respectively. Calculate the change in the kinetic sd+5r6wu*rxf*heeq+eui +-vi d 1b/denergy of the proton as it travels from P to Q. $ \times10^{-20 }\;J$
