A person is sleeping during day time. Why does this happen with some people that they feel sleepy during day time in office or in the classroom. Have you ever come across such situation? Explain.

What will happen, when you sleep under a tree during night time?

Consider a game played by 10 prople in which each flips a fair coin at the same time. If all but one of the coins comes up the same, then the add persons wing (e.g., if there are nine tails and one head then person having lead wins.) If such a situation does not occur, the players flips again. Find the probability that game is settled on or after nth toss.

You might have observed on a dry day that whwn you touvh the screen of a television you get a slight shock. why does it happen?

Using the concept of evaporation explain why does dog pant during hot summer days?

a. A comb run through one's dry hair attracts small bits of paper. Why? What happens if the hair is wet or if it is a rainy day? (A paper does not conduct electricity.) b. Ordinary rubber is an insulator. But special rubber tyres of aircraft are made slightly conducting. Why is necessary? c. Vehicles carrying inflammable materials usually have metallic ropes touching the ground during motion. Why? d. A bird perches on a bare high power line, and nothing happens to the bird. A man standing on the ground touches the same line and gets a fatal shock. Why?

Answer the following questions . a. The earth's magnetic field varies from point is space. Does it also change with time ? It so , on what time scate does it change appreciably ? b. The earth's core is known to contain iron. Yet geologists do not regard this as a source of the earth's magnetism why ? c. The charged currents in the outer conducting regions of the earth's core are thought to be responsible for earth's magnetism . What might be the ' battery ' (i.e., the source of energy) to sustain these currents ? d. The earth may have even reversed the direction of its field several times during its history of 4 to 5 billion years. How can geologists know about the earth's field in such distant past ? e. The earth's field departs from its dipole substantially at large distances (greater than about 30,000 km) what agencies may be responsible for this distortion ? f. Interstellar space has an extremely weak magnetic field of the order of 10^(-12) T, Can such a weak field be of any significant consequence ? Explain. [Note : Exercise 2 is meant mainly to arouse your curiosity . Answers to some question above are tentative or unknown . Brief answers wherever possible are given at the end . For details , you should consult a good text on geomagnetism.]