Use the formula `lambda_mT = 0.29 cm` K to obtain the characteristic temperature ranges for different parts of the electromagnetic spectrum. What do the numbers that you obtain tell you?

The terminology of different parts of the electromagnetic spectrum is given in the text. Use the formula E = hv (for energy of a quantum of radiation: photon) and obtain the photon energy in units of eV for different parts of the electromagnetic spectrum. In what way are the different scales of photon energies that you obtain related to the sources of electromagnetic radiation?

Given below is some famous number associated with electromagnetic radiations in different contexts in physics. State the part of the electromagnetic spectrum to which this number belongs. 2.7 K [temperature associated with the isotropic radiation filling all space-thought to be a relic of the ‘big-bang’ origin of the universe].

Given below are some famous numbers associated with electromagnetic radiations in different contexts in physics. State the part of the electromagnetic spectrum to which each belongs. 21 cm (wavelength emitted by atomic hydrogen in interstellar space).

Use the same formula you employ in to obtain electron speed for a collector potential of 10 MV. Do you see what is wrong? In what way is the formula to be modified?

Find the L.C.M. of the following numbers in which one number is the factor of the other : 9,45. What do you observe in the results obtained.

Find the L.C.M. of the following numbers in which one number is the factor of the other : 12,48 What do you observe in the results obtained.

The Sun is a hot plasma (ionized matter) with its inner core at a temperature exceeding 107 K, and its outer surface at a temperature of about 6000 K. At these high temperatures, no substance remains in a solid or liquid phase. In what range do you expect the mass density of the Sun to be, in the range of densities of solids and liquids or gases ? Check if your guess is correct from the following data : mass of the Sun = 2.0 xx 10^30 kg , radius of the Sun = 7.0 xx 10^8 m .

We wish to obtain an erect image of an object, using a concave mirror of focal length 15cm what should be the range of distance of the object from the mirror? What is the nature of the image ? Is the image larger or smaller than object? Draw a ray diagram to show the image formation in this case.