Question

An electrical iron of power 1.3kw is used for 45 minutes calculate the electrical energy consumed in joule

Answer 1

Given :

$\sf Power = 1.3 kw \\ \\ \sf Time = 45 min = \frac{45}{60} = \frac{3}{4} hr$

Solution :

$\boxed{ \sf \orange{ Power = \frac{Work}{Time}} } \\ \\ \therefore \sf Work = Power \times Time \\ \\ \sf Work = 1.3 \times \frac{3}{4} \\ \\ \sf Work = \frac{3.9}{4} \: kwh \\ \\ \underline{\sf 1kwh = 3.6 \times {10}^{6} J} \\ \\ \sf \frac{3.9}{4} \: kwh = \frac{3.9}{ \cancel{4}} \times \cancel{ 3.6} \times {10}^{6} \\ \\ \large \boxed{ \sf \green{ Work = 3.5 \times {10}^{6}J }}$

Answer 2

Answer:

Given :

\begin{gathered} \sf Power = 1.3 kw \\ \\ \sf Time = 45 min = \frac{45}{60} = \frac{3}{4} hr\end{gathered}

Power=1.3kw

Time=45min=

60

45

=

4

3

hr

Solution :

\begin{gathered} \boxed{ \sf \orange{ Power = \frac{Work}{Time}} } \\ \\ \therefore \sf Work = Power \times Time \\ \\ \sf Work = 1.3 \times \frac{3}{4} \\ \\ \sf Work = \frac{3.9}{4} \: kwh \\ \\ \underline{\sf 1kwh = 3.6 \times {10}^{6} J} \\ \\ \sf \frac{3.9}{4} \: kwh = \frac{3.9}{ \cancel{4}} \times \cancel{ 3.6} \times {10}^{6} \\ \\ \large \boxed{ \sf \green{ Work = 3.5 \times {10}^{6}J }}\end{gathered}

Power=

Time

Work

∴Work=Power×Time

Work=1.3×

4

3

Work=

4

3.9

kwh

1kwh=3.6×10

6

J

4

3.9

kwh=

4

3.9

×

3.6

×10

6

Work=3.5×10

6

J