Two circular coils 1 and 2 are made from the same wire but

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Two circular coils 1 and 2 are made from the same wire but the radius of the 1^st coil is twice that of the 2^nd coil. What potential difference in volts should be applied across them so that the magnetic field at their centres is the same

1. 4
2. 6
3. 2
4. 3
5. None

Correct Option: E

If R₁ & R₂ be the radius of the circular wires,R₁/R₂ = 1/2. If same potential is applied on them, current in Ist will be half that in the later. If V potential is applied on them, current in them

=	V	&	V
	2R		R

Now magnetic field at the centre of circular coil,

=	μ₀I
	2r

For first wire, field B₁ =	μ₀V
	2R × 2R

For second wire, field B₂ =	μ₀V
	2(R/2) × R

Given B₁ = B₂
The given data do not provide any required result. There is a mistake in the framing of the question.