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Frequency of the waves calculation
The electromagnetic waves emitted by the mobile phone have a period of 4.0 × 10⁻¹⁰ s.
Calculate the frequency of the waves. Give your answer in standard form.
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Marking points
- 1 Uses the reciprocal relationship between period and frequency with 4.0 × 10⁻¹⁰ s.
- 2 Rearranges and evaluates the reciprocal correctly.
- 3 Gives 2.5 × 10⁹ Hz in standard form.
Full-mark answer
T = 1/f, so f = 1/T = 1/(4.0 × 10⁻¹⁰) = 2.5 × 10⁹ Hz.
Why this answer loses marks
I left the calculator result as an ordinary number.
The final frequency must be written in normalized standard form to earn the final mark.