Which of the following is not correct? . a a changing electric field can produce a changing magnetic field . b a steady magnetic field produces a steady current . c a changing magnetic field can produce a changing current . d a changing magnetic field can produce a changing current

The Correct answer is B. "A steady magnetic field produces a steady current"

Explanation:

Michael Faraday discovered that the variation of magnetic fields is actually what causes the current to flow, instead of merely the presence of it.

The presence of a steady magnetic field implies that a wire in that field will not manifest any electric current, given that it experiments no variations.

This phenomenon is known as magnetic induction, and by using it we have become able to generate electric power from natural sources such as rivers and wind.

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.