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A moving coil galvanometer has a coil with 175 turns and area 1 cm². It uses a torsion band of torsion constant 10⁻⁶ N m/rad. The coil is placed in a magnetic field B parallel to its plane. The coil deflects by 1° for a current of 1 mA. The value of B (in Tesla) is approximately

Asked in JEE Main 9th April 2nd Shift 2019 · Galvanometer sensitivity and figure of merit

• (1) 10⁻³
• (2) 10⁻¹
• (3) 10⁻⁴
• (4) 10⁻²

Step-by-step solution

Why the other options are wrong

• (2) Converted 1 cm² to 10⁻⁶ m² instead of 10⁻⁴ m².
• (3) Took the current as 10⁻² A (slip in converting 1 mA).
• (4) Took the current as 10⁻⁴ A (slip in converting 1 mA).

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