The CoV (coronavirus) is circular in shape with a diameter of approximately 0.00014 mm. Express

1. Write the number with a coefficient between 1 and 10 and determine the power of 10.

$0.00014 = 1.4 \times 10^{-4}$
The decimal point moves 4 places to the right to get $1.4$, so the power of 10 is $-4$.

1. Convert the diameter from millimetres to metres.

Since $1\text{ mm}=10^{-3}\text{ m}$,

$0.00014\text{ mm}=0.00014\times 10^{-3}\text{ m}$

Using part (a),

$0.00014=1.4\times 10^{-4}$

so

$0.00014\text{ mm}=1.4\times 10^{-4}\times 10^{-3}=1.4\times 10^{-7}\text{ m}.$

2. Convert metres to nanometres using the given conversion.

Given $1\text{ nm}=10^{-9}\text{ m}$,

$1\text{ m}=10^9\text{ nm}.$

Hence

$1.4\times 10^{-7}\text{ m}=1.4\times 10^{-7}\times 10^9\text{ nm}$

$=1.4\times 10^2\text{ nm}=140\text{ nm}.$