Question

When $3\text{g}$ of matter converted into energy, the energy released in $\text{kWh}$ is

• A. $7.5\times {10}^7$
• B. $5\times {10}^7$
• C. $2.5\times {10}^7$
• D. $3.5\times {10}^7$

Answer 1

The correct option is A $7.5\times {10}^7$

According to Einstein's mass energy equivalence,

$E=m{c}^2$

$\Rightarrow E=3\times {10}^{-3}\times (3\times {10}^8{)}^2$

$\Rightarrow E=27\times {10}^{13}\text{J}$

We know that,

$1\text{kWh}=36\times {10}^5\text{J}$

$\Rightarrow E=\frac{27\times {10}^{13}}{36\times {10}^5}\text{kWh}$

$\Rightarrow E=7.5\times {10}^7\text{kWh}$

Hence, option $\left(A\right)$ is correct.