Q.

The figure shows a circular loop made of a wire of radius R. The resistivity of the material varies as a function of  θ such that  ρ=ρ0sin2⁡θ. The positions of the Jockey such that the magnetic field at the centre (O) due to the current in the loop is zero, will be

see full answer

Want to Fund your own JEE / NEET / Foundation preparation ??

Take the SCORE scholarship exam from home and compete for scholarships worth ₹1 crore!*
An Intiative by Sri Chaitanya

a

θ=π2

b

θ=π

c

θ=3π2

d

θ=π4

answer is A.

(Unlock A.I Detailed Solution for FREE)

Ready to Test Your Skills?

Check your Performance Today with our Free Mock Test used by Toppers!

Take Free Test

Detailed Solution

Consider two sectors one of  α and other of (2π−α)B at O will be zero if I1α=I2(2π−α) ⇒I1=ER1 ,⇒ I2=ER2 So αR1=2π−αR2 ⇒R1=∫0αρ0sin2⁡θA Rd θ =ρ0RAα-sin2α2∵∫sin2θdθ=12x-sinθcosθ+CSimilarly  we can get  R2=∫α2πρ0sin2⁡θA Rd θ =ρ0RA2π-α+sin2α2 ∴αR2=2π-αR1⇒αρ0RA2π-α+sin2α2=2π-αρ0RAα-sin2α2 ⇒sin2α=0Onsolvingweget  α=π2,π,3π2
Watch 3-min video & get full concept clarity
score_test_img

Get Expert Academic Guidance – Connect with a Counselor Today!

whats app icon