A transformer is used to light a lamp rated 40w, 240v from a 400v A. C supply. Calculate: A. The ratio of the number of turns of the primary to the secondary coil.
B. Current drawn from the main circuit if the efficiency of the transformer is 90%.

Unpolarized light of intensity so passes through two sheets of polarizing material whose transmission axes make an angle of 60∘ with each other as shown in the figure. what is the intensity of the transmitted beam, st?

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Select for each of the following statements whether it is correct or incorrect. (a) in an isothermal expansion of an ideal gas. (b) the temperature remains constant. (b) the pressure remains constant. (c) there is work done by the gas. (d) there is heat added to the gas. (e) the change in internal energy equals zero.