Question

Calculate the electric energy consumed in units when a 60 W bulb is used for 10 hours.

Answer 1

Hint: Using the electric energy formula,\[\boxed{E = P \times t}\]
Where E = Electric energy, P = Power & t = time.

Complete step by step solution:
Power of a bulb of 60 W means that the bulb is used 60 Joules energy in 1 hour.\[\boxed{P = \dfrac{W}{t}}\]
Where P = Power, W = Work done & t = time
According to question, given that,
P = 60 W
t = 10 hours
E =?
By the formula of electric energy,\[\boxed{E = P \times t}\]
\[\Rightarrow E = 60 \times 10 \times 3600\]\[\left( {\because 1h = 3600\sec } \right)\]
\[\Rightarrow E = 60 \times 36000\]\[Joule\]
\[\Rightarrow 216 \times {10^4}\]\[Joule\]
For converting in units, we use a formula,
\[\Rightarrow E\left( {unit} \right) = \dfrac{{E\left( {Joule} \right)}}{{3.6 \times {{10}^6}}}\]
\[\Rightarrow \dfrac{{3600 \times 60 \times 10}}{{3.6 \times {{10}^6}}}\]
\[\Rightarrow E = \dfrac{6}{{10}}\]
\[\Rightarrow E = 0.6\] Units

Note: We find out the electric energy in Joules, if we take energy in joule which is S.I unit of energy so that we take the time in second because second is the S.I unit of time, and we have to show the energy in the terms of unit, so we have to divided the electric energy by because after divide this we got the answer in the unit terms that is kilowatt hour(KWH).