Magnetic Effects & Magnetism

JEE Main level, single correct, medium

178 of 276

Question 178 of 276

A uniform electric field and a uniform magnetic field are acting along the same direction in a certain region. If an electron is projected along the direction of the fields with a certain velocity then

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Answer: (A) its velocity will decrease.

F⃗=−e[E⃗+v⃗×B⃗]=−eE⃗\vec{F}=-e[\vec{E}+\vec{v} \times \vec{B}]=-e \vec{E}
a⃗=−eE⃗m\vec{a}=-\frac{e \vec{E}}{m}
v(t)=v∘−eEmtv(t)=v_{\circ}-\frac{e E}{m} t

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