Question

solve this question.​

Answer 1

$\large\underline{\bigstar \: \: {\sf Given-}}$

• Electric room heater has Resistance (R) = 25Ω
• Voltage (V) = 220V
• Time (t) = 12 min

$\large\underline{\bigstar \: \: {\sf To \: Find -}}$

• Heat dissipated by it ( in kJ)

$\large\underline{\bigstar \: \: {\sf Formula \: Used -}}$

$\color{violet}\bullet\underline{\boxed{\sf H=\dfrac{V^2}{R}t}}$

$\large\underline{\bigstar \: \: {\sf Solution-}}$

Convert minutes into seconds -

$\implies{\sf 1\:min=60\:s }$

For 12 mins

$\implies{\sf 12 \times 60 }$

$\implies{\sf 720\:s }$

$\implies{\sf H=\dfrac{V^2}{R}t }$

$\implies{\sf \dfrac{(220)^2}{25}\times720}$

$\implies{\sf \dfrac{44000}{25}\times720}$

$\implies{\sf \dfrac{31680000}{25}}$

$\implies{\sf 1267200 \:J }$

$\implies{\sf \dfrac{1267200}{1000} }$

$\color{red}\implies{\sf H=1267.2\:kJ}$

$\large\underline{\bigstar \: \: {\sf Answer-}}$

Heat Energy dissipated by it is $\color{red}{\sf 1267.2\:kJ}$

Answer 2

Given ,

Resistance (R) = 25 ohm

Potential difference (v) = 220 v

Time (t) = 12 min or 720 sec

We know that ,

The amount work done in maintaining the electric current in a circuit for a given time is called electric energy

It is denoted by " E "

$\large \mathtt{ \fbox{Electric \: energy = \frac{ {(v)}^{2} \times t }{R} }}$

Thus ,

E = ((220)² × 720)/25

E = (484 × 72 × (10)³)/25

E = 34848 × (10)³/25

E = 1393.92 × (10)³ joule

In terms of kilo joule

E = 1393.92 kilo joule

Hence , the electric energy is 1393.92 kilo joule