UPSEE Solved Model Paper 2

Given v = (2×105

^

i

)ms−1. The force vector is given by

→

F

= q(

→

v

×

→

B

)
= q{2×105

^

i

×(

^

i

−4

^

j

−3

^

k

)}
= 2×105×q(−4

^

k

+3

^

j

)
Therefore, the y and z components of the force are
Fy = 6×105×q
and Fz = −8×105×q
∴ Magnitude of force = √Fy2+Fz2
= q√(6×105)2+(−8×105)2
= q×10×105
= 1.6×10−19×10×105
= 1.6×10−13N, which is choice (3).