Use the following formulae to solve these questions. Show your workings and state units for all answers.
1. An electric lamp transfers 500 J in 5 s. What is its power?
2. A device transfers 100 J in 5 s. What is its power?
3. How much energy is transferred by a 5 W lamp in 2 minutes?
4. Which is the greatest power rating? 300W, 0.3kW or 3000W
5. What is the power of a lamp with a current of 5A and potential difference of
1.5V?

1 p=e÷t so the answer for the first one is 100

if the thermos has a vacuum innner, then heat through conv currents and conduction are reduced = vacuum flask

answer: 802.3 kilo joules of energy represents 191.75 kilo calorie of energy.

explanation:

energy released during combustion of one mole methane = 802.3 kilo joules

if 1 kilo joule = 0.239006   kilo calorie

then ,802.3 kilo joule will be = 802.30.239006 kilo calorie

802.3 kilo joule = 191.75 kilo calorie

hence, the energy in kilo calorie is 191.75 kilo calorie.