AP EAPCET 19-Aug-2021 Shift 2 Paper

Given, initial magnetic field at centre of single turn coil =B
Final number of turn, n2=2
Let final magnetic field be B'
∵B=

µ0

2

I

R

where, µ0 is permeability,
I is current,
R is radius,
But length l of conductor is same.
⇒l=2πR=2×2πR′
⇒R=

R

2

Now,B∝

n

R

∴

B′

B

=

2

R 2

×

R

1

=4
⇒ B' = 4B