A proton moving with velocity v is acted upon by electric field E and magnetic field B. The proton will move undetected, if

Question

A proton moving with velocity v is acted upon by electric field E and magnetic field B. The proton will move undetected, if (A) E is perpendicular to B (B) E is parallel to v and perpendicular to B (C) E, B and v are mutually perpendicular and v=(E/B)  (D) E and B both are parallel to v

Tardigrade Admin · Accepted Answer

If magnetic field B, and electric field E are perpendicular to the direction of motion of proton, then proton will move without any deflection. So, magnetic force = electric force. e v B=e E ∴ v=(E/B) ∴ E , B and v are mutually perpendicular and v=E / B

Q. A proton moving with velocity $v$ is acted upon by electric field $E$ and magnetic field $B$ . The proton will move undetected, if

E is perpendicular to B

E is parallel to v and perpendicular to B

E, B and v are mutually perpendicular and $v = \frac{E}{B}$

E and B both are parallel to v

If magnetic field $B$ , and electric field $E$ are perpendicular to the direction of motion of proton, then proton will move without any deflection.
So, magnetic force = electric force. $e v B = e E$
$∴ v = \frac{E}{B}$
$∴ E, B$ and $v$ are mutually perpendicular and $v = E / B$

Q. A proton moving with velocity v is acted upon by electric field E and magnetic field B. The proton will move undetected, if