Answer:
(A) q/m = 9.58 x 10⁷ C/kg
(B) b. Proton
Explanation:
(A)
In order to pass un-deflected between magnetic and electric field both electric and magnetic forces must be equal:
Felectric = Fmagnetic
Eq = Bqv
v = E/B ------------ equation (1)
Now, when the particle forms semi-circle under influence of magnetic field. At this, point magnetic field is equal to centripetal force:
Centripetal Force = Magnetic Force
mv²/r = qvB
mv = qrB
v = qrB/m ------------ equation (2)
comparing equation (1) and equation (2), we get:
E/B = qrB/m
q/m = E/B²r
where,
q/m = charge to mass ratio = ?
E = Electric Field = 187500 V/m
B = Magnetic Field = 0.125 T
r = radius of circular path = 25.05 cm/2 = 12.525 cm = 0.12525 m
Therefore,
q/m = (187500 V/m)/(0.125 T)²(0.12525 m)
q/m = 9.58 x 10⁷ C/kg
(B)
This is the charge to mass ration of a proton:
q/m = 1.6 x 10⁻¹⁹ C/1.67 x 10⁻²⁷ kg
q/m = 9.58 x 10⁷ C/kg
Therefore, correct option is:
b. proton
