Question

The wrong unit conversion among the following is

• A. 1 angstrom = ${10}^{-10}m$
• B. 1 fermi = ${10}^{-15}$ m
• C. 1 light year = $9.46\times {10}^{15}m$
• D. 1 astronomical unit = $1.496\times {10}^{-11}m$

Answer 1

Answer: (D)

1 astronomical unit = $1.496\times {10}^{-11}m$

$A)1$Angstrom: $1$ Ångström is equal to$0.1$nanometers. Expressed in the SI base unit meters $1$ Ångström is equal to $1\times {10}^{-10}$ meters. $1\AA =0.0000000001m.$

$B)$Definition of fermi unit: $\equiv 1\times {10}^{-15}m.$

$C)$The light-year is a unit of length used to express astronomical distances and measures about $9.46$ trillion kilometres $(9.46\times {10}^{12}km)$ or $5.88$ trillion miles $(5.88\times {10}^{12}mi).$

$D)$The total radiation power received from the sun on a unit area perpendicular to the sun rays at the mean earth-sun distance, termed an astronomical unit, is called the solar constant (SC), where $1$ astronomical unit $=1AU=1.496\times {10}^{11}m.$

So $D$ is wrong unit conversion