Verified Solution • 2025–26 Session
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QAIPMT-2006-Ph-2431: NEET 2006 Physics - Class 12 AIPMT-2006-Ph-2431 Solution: Two circular coils 1 and 2 are made from the same wire but the…
Two circular coils 1 and 2 are made from the same wire but the radius of the 1st coil is twice that of the 2nd coil. What is the ratio of potential difference in volts should be applied across them so that the magnetic field at their centres is the same?
Multiple Choice Options
- A 3
- B 4
- C 6
- D 2
Step-by-Step Verified Solution
Let r 1 and r 2 are the radius of coil 1 and 2. If B 1
and B 2 are magnetic induction at their centre,
then
B 1 = _ 0 I 1 2 r 1 and B 2 = _ 0 I 2 2 r 2
Since B 1 = B 2 ; and r 1 = 2r 2
therefore I 1 = 2I 2 .
Again if R 1 and R 2 are resistance of the coil 1
and 2 then R 1 = 2R 2 (as R _ length = 2 � r) and if
V 1 and V 2 are the potential difference across
them respectively, then
V 1 V 2 = I 1 R 1 I 2 R 2 = ( 2 I 2 ) ( 2 R 2 ) I 2 R 2 = 4