The correct option is C −6^i−6^j−8^k
Given:
q=1
→v=2^i+4^j+6^k
→B=B^i+B^j+B0^k
→F=4^i−20^j+12^k
Now,
→F=q(→v×→B)
⇒4^i−20^j+12^k=1[(2^i+4^j+6^k)×(B^i+B^j+B0^k)]
⇒4^i−20^j+12^k=(4B0−6B)^i−(2B0−6B)^j+(−2B)^k
On comparing and solving, we get,
B=−6 and B0=−8
Therefore,
→B=B^i+B^j+B0^k=−6^i−6^j−8^k
Hence, option (C) is the correct answer.