So let's start with...
WHAT is Power ??
Power can be described as the rate at which the work is performed.
It is defined as the amount of work completed/done in specified/unit time.
Power is a time-based quantity.
It's a scalar quantity.
the above stated formula can also be framed as ,
POWER = TORQUE x ANGULAR VELOCITY
WHAT units are used to measure Power ??
S.I Unit : J/sec ( Watt )
CGS Unit : erg/sec
WHICH instruments / measuring device is used to measure Force ??
Well there aren't any such specific devices that can measure power, as power is quantity that is determined using other factors like Force, Time, Velocity, Torque, Displacement, Voltage, Current & Resistance.
We can measure Power by using instruments that can determine the value of the factors that are used to calculate power and then substitute it in the formula of Power depending on what type of Power is to be measured.
Eg: We cannot directly measure the Electric Power but same can be done easily by determining it's Voltage, Current and Resistance.
NOTE: Proper explanation to the above example given ahead under title 'Electrical Power'.
WHAT types of Power are there ??
Mechanical power
Electrical Power, etc
What is Mechanical Power ??
The rate at which work can be performed is referred to as mechanical power.
It is a power output, as opposed to a power input.
Power can also be described as the transfer of energy in specific amount of time.
The formula of Mechanical power changes depending on the case given.
Eg: The formula for finding Mechanical Power of an engine in airplane is not the same as the one used for calculating power of a pupil running up stairs.
Mechanical Power is not always calculated in Joules/second but in terms of Horsepower (HP) also.
Eg: The power of an engine is always given in terms of horsepower (HP) and not J/sec.
Most often the term Mechanical Power is used while referring to power of an engine whether it's of Car, Bike, Ship or an Airplane.
It is also used to describe to the power of human in performing task.
Eg:
In the Fig. given below Mr.A and Mr.B are expected to climb the stairs. Mr.A takes 15 seconds to climb the stair whereas Mr.B takes 10 seconds to climb the same number of stairs. Here can we say that Mr.B has more power than Mr.A as Mr.B climbed up same amount of stairs quicker that Mr.A . As the amount of work done by both of them is same but the time taken by them is different.
Lets consider a example of a Ferrari and Ford car. A Ferrari car takes just 3 sec for 0-100kmph whereas, a Ford would take 7.05 sec for 0-100kmph. Here we can consider the work to be as reaching from0-100kmph, where the Ferrari took just 3 sec and Ford took 7.05 sec. We can say that Ferrari has more power than Ford.
the basic thing to understand over here is that lower the amount of time taken to perform work higher is the Power.
WHAT is Electrical Power ??
Electric power is the rate, per unit time, at which electrical energy is transferred by an electric circuit.
Electric power is typically produced by generators, but it may also be generated by sources such as electric batteries.
Electric power can be delivered over long distances via transmission lines and used for high-efficiency applications such as motion, illumination, or heat.
As electric charges pass through an electric potential difference (voltage), which occurs in electrical components in electric circuits, they are converted to other forms of energy.
Eg: Let us consider a Circuit that has a battery of voltage 20V and a lamp with resistance of 3ohms. Now we are supposed to calculate the power dissipated by lamp in terms of both Light and Heat.
Here we cannot directly measure the Power of Lamp but the same is possible by using a Multimeter which can measure Voltage, Current and Resistance. the values obtained by them is further substituted in the formula of Power.
Yes, such device that can created that is connected with multimeter as whole and the readings of V, I & R are conveyed to the Device and the device operates on a logic circuit which automatically calculates the Power on real time basis.
The power of electrical circuit can increased by increasing Voltage of the battery of by lowering the resistance of the lamp up to safety margin.
So we can conclude that, Power is much required for consumer/individual to recognize his belongings true potential i.e if one buys a car it's of utmost importance to check it's power output and it's effect on other aspects of the car. Similar is the case for Bikes, Ships & Airplanes. Also we can Power enables us to recognize our needs as in if an interior development work is on the card then the lighting of the house is the main aspects that enhances the looks of our property. Great lighting comes at the cost of electricity bill and the requisites of that lighting product. Every lighting product as well as all the electrical equipment come with their power output which should be matched according to our requirements and then purchased. Imagine buying a 2ton Ac for just a 300sq.ft room, yes it would work phenomenally in cooling the room but at the cost of Electricity bills. Power of an equipment enables us to decides to best product for our requirements and ability.