Question

The wavelength of yellow light in a spectrum is about 0. 00002 inches. Which

number best approximates this length as a power of 10?

A. 2 x 105

B. 2 x 10-4

C. 2x 10-5

D. -2 x 105

Answer 1

C. 2 × 10^-5

Explanation:

You want the number 0.00002 inches expressed using scientific notation.

Scientific notation

A number written in scientific notation has all of its significant digits in the mantissa, with exactly one of them to the left of the decimal point. The multiplier is written as a power of 10. The appropriate power corresponds to the place-value multiplier of the most-significant digit.

The number 0.00002 is "two hundred-thousandths". That is, it is two multiplied by one hundred-thousandth, or 1/100,000 = 1/10^5 = 10^-5. The length in scientific notation is ...

2 × 10^-5 inches

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Additional comment

Different authors name the parts of a number in scientific notation differently. The two attachments show some of the differences.