c
(c) \(\overrightarrow {v\,} = 2 \times {10^5}\hat i \)and \(\overrightarrow B = (\hat i + 4\hat j - 3\hat k)\)
\(\overrightarrow F = q\,(\overrightarrow {v\,} \times \overrightarrow B ) = - 1.6 \times {10^{ - 19}}[2 \times {10^5}\hat i \times (i + 4\hat j - 3\hat k)]\)
\( = - 1.6 \times {10^{ - 19}} \times 2 \times {10^5}[\hat i \times \hat i + 4(\hat i \times \hat j) - 3(\hat i \times \hat k)]\)
\( = - 3.2 \times {10^{ - 14}}[0 + 4\hat k + 3\hat j] = 3.2 \times {10^{ - 14}}( - 4\hat k - 3\hat k)\)
\(==>\) \(|\overrightarrow F |\, = 3.2 \times {10^{ - 14}} \times 5 = 1.6 \times {10^{ - 13}}N.\)