Huge quantities of electricity are discharged in light flashes and temperatures of over ____`"^@C` or more can be reached.

The quantity of heat required to raise the temperature of 1 gm of water by 1^@C is ____

An electric heater of resistance 10Omega connected to 220 V power supply is immersed in the water of 1 kg. How long the electrical heater has to be switched on to increase its temperature from 30^(@)C to 60^(@)C . (The specific heat of water is s=4200J kg^(-1) /C )

A 50 kg man is running at a speed of 18 kmh^(-1) If all the kinetic energy of the man can be used to increase the temperature of water from 20^(@)C to 30^(@)C .How much water can be heated with this energy?

A metal block of heat capacity 90J//.^(@)C placed in a room at 25^(@)C is heated electrically. The heater is switched off when the temperature reaches 35^(@)C . The temperature of the block rises at the rate of 2^(@)C//s just after the heater is switched on and falls at the rate of 0.2^(@)C//s just after the heater is switched off. Assume Newton's law of cooling to hold (a) Find the power of the heater. (b) Find the power radiated by the block just after the heater is switched off. (c ) Find the power radiated by the block when the temperature of the block is 30^(@)C . (d) Assuming that the power radiated at 30^(@)C respresents the average value in the heating process, find the time for which the heater was kept on.

We can see things around us only when the light reflected by them reaches our eyes.

The coefficients of thermal conductivity of copper, mercury and glass are respectively K_c , K_m and K_g such that K_c > K_m > K_g . If the same quantity of heat is to flow per second per unit area of each and corresponding temperature gradients are X_c , X_m and X_g , then

A glass contains some water at room temperature 20^(@)C .Refrigerated water is added to it slowly. When the temperature of the glass reaches 10^(@)C, small droplets condense on the outer surface. Calculate the relative humidity in the room. The boiling point of water at a pressure of 17.5mm of mercury is 20^(@)C and at 8.9mm of mercury is 10^(@)C .

Find the temperature at which the everage thermal kinetic energy is equal to the energy needed to take a hydrogen atom from its ground state n = 3 state hydrogen can now emit rod light of wavelength 653.1 nm because of maxwellan distribution of speeds a hydrogen sample emits red light at temperature much lower than that obtained from this problem Asuume that hydrogen that hydrogen molecules dissociate into atoms

A gas is enclosed in a cylindrical can fitted with a piston. The walls of the can and the piston are adiabatic. The initial pressure , volume and temperature of the gas are 100 kPa, 400cm^(3) and 300K respectively. The ratio of the specific heat capacities of the gas is (C_p / C_v = 1.5) Find the pressure and the temperature of the gas if it is (a) suddenly compressed (b) slowly compressed to 100 cm^(3) .

Electric field lines are a pictorial representation of the electric field around charges. A. State Gauss's Law in Electrostatics. B. Using this law derive an expression for the electric field intensity due to a uniformly charged thin spherical shell at a point. i. Outside the shell ii. Inside the shell C. Suppose that you are in a cave deep withing the earth. Are you safe from thunder and lighting? Why?