Question

CGS unit of power is $erg{\text{ }}{s^{ - 1}}$ ?
A. True
B. False

Answer 1

Hint : Using the formula of power and getting the unit of each component from the formula of power and putting them according to the formula that is ${\text{power}} = \dfrac{{{\text{work done}}}}{{{\text{time}}}}$ . CGS unit of work done and time derives the CGS unit of power.

Complete Step By Step Answer:
We know that the rate of doing work is known as Power. Also we can say that work done per unit time is known as power. Its formula is given by:
${\text{power}} = \dfrac{{{\text{work done}}}}{{{\text{time}}}}$
Also, $P = \dfrac{W}{t}$
where $P$ is power
$W$ is work done
$t$ is time.
Now SI unit of work is joule and SI unit of time is second therefore SI unit of power is joule per second.
SI unit of $P = \dfrac{{{\text{joule}}}}{{{\text{second}}}}$
But, CGS unit of work done is erg and CGS unit of time is second therefore CGS unit of power is erg per second.
CGS unit of $P = \dfrac{{{\text{erg}}}}{{{\text{second}}}}$ .
Power is said to be 1 erg per second when one erg of work is done in one second. Erg is equal to ${10^{ - 7}}$ joule.
Hence it is true that the SI unit of power is $erg{\text{ }}{s^{ - 1}}$ .
Therefore the correct answer is option A.

Note :
Erg can be said $100$ nano joules in SI units. Also the power in the SI unit can be said as $100$ nano joules per second. There are various other units of power but the most used unit is watt. It is also the S.I. unit of power. It is kept in the name of James watt.