Question

An immersion heater is rated 836 watt. It should heat 1 litre of water from 20^o C to 40^o C in about

• A. 200 sec
• B. 100 sec
• C. 836 sec
• D. 418 sec

Answer 1

Answer: (B)

100 sec

Answer 2

By using $t = \frac{4180 \times n \times \Delta\theta}{P}$

⇒ $t = \frac{4180 \times 1 \times (40 - 20)}{836} = 100\sec$