An ordinary electric fan does not cool the air, still it gives comfort in summer. Explain.

Will the cool drinks give more fizz at top of the hills or at the foot ? Explain .

Solar water heater does not produce electricity . Give reason.

Two large conducting spheres carrying charges Q_1, and Q_2, are brought close to each other. Is the magnitude of electrostatic force between theme exactly given by (Q_1Q_2)/(4pi epsi_(0) r^(2)) , where r is the distance between their centres? b. If Coulomb's law involved 1/r^(3) dependence ("instead of "1/r^2), would Gauss law be still true? c. A small test charge is released at rest at a point in an electrostatic field configuration. Will it travel along the field line passing through that point? d. What is the work done by the field of a nucleus in a complete circular orbit of the electron? What if the orbit is elliptical? e. We know that electric field is discontinuous across the surface of a charged conductor. Is electric potential also discontinuous there? f. What meaning would you give to the capacitance of a single conductor? g. Guess a possible reason why water has a much greater dielectric constant (=80) than say, mica (= 6).

True or False.if False,give the correct statement: When the air around the clouds is cool, these drops of water fall in the form of snow or rain.

An element A belongs to 14th group is a metal, which can be cut with a knife. It is not a good conductor of heat and electricity. A in pure state does not react with water but air dissolved water forms hydroxide. Identify A.

In discussing Doppler effect, we use the word "apparent frequency". Does it mean that the frequency of the sound is still that of the source and it is some physiological phenomenon in the listener's ear that gives rise to Doppler effect ? Think for the observer approaching the source and for the source approaching the observer.