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The amplitude of the magnetic field of an electromagnetic wave is 510 nT, then the amplitude of the electric field of this wave is ______ V m⁻¹.

Asked in GSEB Board July 2021 · E0 = cB0 and E/B = c

• (1) 1.53×10⁻⁷
• (2) 153
• (3) 1.7×10⁻⁶
• (4) 170

Step-by-step solution

Why the other options are wrong

• (1) comes from keeps the nano prefix in the answer. The number 153 is right, but 153 nV m⁻¹=1.53×10⁻⁷ V m⁻¹; the prefix belonged to the given B₀, not to E₀.
• (3) comes from dividing by c instead of multiplying, with the prefix dropped: (510)/(3×10⁸)=1.7×10⁻⁶.
• (4) comes from dividing the bare 510 by 3 and letting the powers of ten look after themselves: (510)/3=170.

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