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The maximum value of E in an electromagnetic wave is equal to 27 V m⁻¹. Thus the maximum value of B is _______.

Asked in GSEB Board March 2016 · E0 = cB0 and E/B = c

• (1) 6×10⁻⁸ T
• (2) 3×10⁻⁶ T
• (3) 9×10⁻⁸ T
• (4) 2×10⁻¹⁰ T

Step-by-step solution

Why the other options are wrong

• (1) 6×10⁻⁸ T is (E₀)/c for E₀=18 V m⁻¹. With 27 V m⁻¹ the answer is half again as large.
• (2) comes from no single slip produces 3×10⁻⁶ T. Sanity check: B₀=(E₀)/c=(27)/(3×10⁸)=9×10⁻⁸ T, some thirty times smaller than this option.
• (4) 2×10⁻¹⁰ T is about 450 times smaller than (E₀)/c; no step in this calculation produces it.

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