Magnetic Effects Of Current Question 4
Question 4 - 2024 (27 Jan Shift 1)
A proton moving with a constant velocity passes through a region of space without any change in its velocity.
If $\overrightarrow{E}$ and $\overrightarrow{B}$ represent the electric and magnetic fields respectively, then the region of space may have :
(A) $E=0, B=0$
(B) $E=0, B \neq 0$
(C) $E \neq 0, B=0$
(D) $E \neq 0, B \neq 0$
Choose the most appropriate answer from the options given below :
(1) (A), (B) and (C) only
(2) (A), (C) and (D) only
(3) (A), (B) and (D) only
(4) (B), (C) and (D) only
Show Answer
Answer: (3)
Solution:
Net force on particle must be zero i.e. $q \vec{E}+q \vec{V} \times \vec{B}=0$
Possible cases are
(i) $\overrightarrow{E} \& \overrightarrow{B}=0$
(ii) $\overrightarrow{V} \times \overrightarrow{B}=0, \overrightarrow{E}=0$
(iii) $q \vec{E}=-q \vec{V} \times \vec{B}$
$\overrightarrow{E} \neq 0 \& \overrightarrow{B} \neq 0$
