Most Important Selected Qs for JEE AdvancedPhysicsMagnetic Effects of Current
Paragraph: Two long parallel wires carrying currents 2.5 amp and I amp in the same direction as shown in figure. An electron moving with a velocity 4 10^5 ~m / sec . as shown in figure and experiences a force of magnitude 3.2 10⁻²⁰ ~N at the point R . Then Question: The position between PR at which a third long parallel wire carrying current 2.5 amp may be placed such that magnetic induction at R is zero.
Options
- Aat 1 m from R and the direction of current is inward.
- Bat 1 m from R and the direction of current is outward
- Cat 1 m from P and the direction of current is inward.
- Dat 1 m from P and the direction of current is outward
Correct answer
B. at 1 m from R and the direction of current is outward
Step-by-step solution
F=q v B =q v B ( =90^ ) So, B= F q v = 3.2 10⁻²⁰ 1.6 10⁻¹⁹ 4 10^3 =5 10⁻⁷ ~T Now, ₀ 2 [ I_p 5 + I_q 2 ]=5 10⁻⁷ I =4 amp If the distance of point R from third current carrying current is X , then aligned & B_R=0 & ₀ 4 2 2.5 | | +5 10⁻⁷=0 & so x= 1 ~m aligned