A

D

B

C

µ

8

0

R

i

µ

4

0

R

i

µ

8

0

R

i

µ

3

0

R

i

By Team Aakash Byju's | 12th December 2022

The Magnetic Field at the Centre of a Circular Arc Inclined at π/2 is

Detailed Explanation

The correct answer is  option A.

µ

8

0

R

i

Arrow

Given that, the arc subtends an angle π/2 at the centre. Hence, it is a right angle.

Curved Dotted Line

C

Let us visualise the given situation - the centre of the circle is C and the radius  is R.

>

π

2

R

R

To find the magnetic field at the centre of the arc as shown in the image, we need to apply Biot Savart's Law. The magnetic field due to a current-carrying arc is

idlsin(90)

=

dB = 

µ

0

4

π

Curved Dotted Line

C

µ

4

0

idl

R

2

R

2

π

π

2

>

R

R

(because sin(90) = 1)

To find the net charge, we take the integration of this magnetic field,

dB =∫

idl

=>

B =

i

dl

R

R

2

2

Curved Dotted Line

C

µ

4

0

π

µ

4

0

π

>

π

2

R

R

Since

we get,

dl

= Rθ

B =

i

Given,

θ

=

π

2

=>

B =

i

R

π

2

=

(Hence the answer.)

Curved Dotted Line

C

R

2

µ

4

0

π

µ

4

0

π

µ

8

0

R

i

π

2

>

R

R