How much has a filament diameter decreased due to evaporation if the mainteenance of the previous temperature required an increase of voltage by `eta=1.0%`. The amount of heat transferred from the filament to surrounding space is assumed to be proportional to the filament surface area.

A metal ball of mass 1.0 kg is kept in a room at 15^(@)C . It is heated using a heater. The heater supplies heat to the ball at a constant rate of 24 W. The temperature of the ball rises as shown in the graph. Assume that the rate of heat loss from the surface of the ball to the surrounding is proportional to the temperature difference between the ball and the surrounding. Calculate the rate of heat loss from the ball when it was at temperature of 20^(@)C .

An incandesent bulb has a thin filament of tungsten that is heated to high temperature by passing an electric current The hot filament emits black-body radiation The filament is observed to break up at random locations after a sufficiently long time of operation due to non-uniform evapo ration of operation due to non-uniform evapo ration of ungsten from the filament If the buld is powered at constant voltage which of the following statement (s) is (are) ture ? .

A truck of mass M has 4 wheels. The surface area of the metal disc in each wheel is A. When brakes are applied the brake shoe in each wheel rubs against the metal disc. This produces heat. We will assume that this heat is used to heat the disc in the wheel only. Each disc has mass m and is made of material of specific heat capacity s. One day the truck was going downhill on a road inclined at angle theta to the horizontal. To maintain a constant speed v the driver had to apply brakes. The only other dissipative force, apart from the brake force, on the truck is the air resistance force that is equal to F. Assume no heating of discs due to air friction. (a) Find the initial rate of rise of temperature of each metal disc after the brakes are applied. (b) Find the final temperature (T) of the disc assuming that it is a black body and it loses heat only through radia- tion. Take the atmospheric temperature to be T_(0)

A thermocol vessel contains 0.5kg of distilled water at 30^(@)C . A metal coil of area 5 xx 10^(-3) m^(2) , number of turns 100 , mass 0.06 kg and resistance 1.6 Omega is lying horizontally at the bottom of the vessel. A uniform time-varying magnetic field is set up to pass vertically through the coil at time t = 0 . The field is first increased from zero to 0.8 T at a constant rate between 0 and 0.2 s and then decreased to zero at the same rate between 0.2 and 0.4s . the cycle is repeated 12000 times. Make sketches of the current through the coil and the power dissipated in the coil as function of time for the first two cycles. Clearly indicate the magnitude of the quantities on the axes. Assumes that no heat is lost to the vessel or the surroundings. Determine the final tempreture of water under thermal equilibrium. Specific heat of metal = 500 j kg^(-1) K^(-1) and the specific heat of water = 4200 j kg^(-1) K^(-1) . Neglect the inductance of coil.

It is observed that when acid and bases react, some energy is released due to neutralization reaction. While in case of strong acid and bases, the energy released in greater, in case of weaker acids of bases, energy released will be lesser. The difference is attributed to energy required for ionization. From the above information and data below answer the questions that follow: Delta H_("neutrization SA/SB") =-57.5 kJ/equivalent, DeltaH_("ionization") of NH_(4)OH =10kJ/mole, DeltaH_("ionization") " of " H_(2)C_(2)O_(4) =20kJ/ mole. What will be final temperature attained if all the heat release in neutralization of 1 L of 0.2 M NH_(4)OH with 2 L of 0.1 M HCl increase the temperature of the final solution having density 0.95gm/ ml and specific heat capacity= (1)/(3) J//gm^(@)"C" if original temperature was 27^(@)"C" ? Assume weak base to be completely unionized.