1. An unknown lamp placed 6m from a photometer screen provides the same illuminance as a 90 cd lamp placed 4 m from the screen.  What is the candlepower of the unknown lamp? 2. The illuminance of a room 20 ft x 15 ft is being designed.  The illuminance required is 50 footcandles.  What is the total required lumens output of the lamp assuming room and luminaire efficiency of 42%?

A 2 x 2 m flat plate solar collector for domestic hot water heating is shown in the figure. The incident solar radiation on the glass cover, which transmits 90% of the incident flux, is 750 W/m2. Water flows through the tubes soldered to the backside of the absorber plate, entering at a temperature of 25°C. The temperature of the glass cover is 27°C, and it radiates heat with an emissivity of 0.92 to the sky at –50°C. Additionally, the glass cover losses heat by convection to air at 20°C flowing over its surface at 30 km/h. Assume that the radiation heat transfer between the absorber plate and glass cover and the heat transfer through the back and sides of the collector is negligible.

A 50-L electrical radiator containing heating oil is placed in a 50-m³ room. Both the room and the oil in the radiator are initially at 5°C. The radiator with a rating of 3 kW is now turned on. At the same time, heat is lost from the room at an average rate of 0.3 kJ/s. After some time, the average temperature is measured to be 20°C for the air in the room, and 60°C for the oil in the radiator. Taking the density and the specific heat of the oil to be 950kg/m³ and 2.2kJ/(kg °C), respectively, determine how long the heater is kept on. Assume the room is well-sealed so that there are no air leaks.

Calculate the power radiated by a woodstove of dimensions 65 cm high by 55 cm deep by 85 cm wide with a surface temperature of 120°C. Assume that heat is radiated from all surfaces of the stove and that the stove has an emissivity of 1. Note that woodstoves are painted black because black surfaces have high absorptance, and objects with high absorptance also have high emissivity.

Determine the luminous efficacy of the following lamps having comparable illumination outputs:a. A 300 W incandescent lamp that emits 5820 lmb. Two 32 W linear fluorescent lamps that emit 2950 lm per lamp in a luminaire that consumes 70 W including the ballastsc. A 70 W metal halide lamp that consumes 88 W, including the ballast and emits 5500 lm

A spring-loaded piston-cylinder device contains 1.5 kg of carbon dioxide. This system is heated from 200 kPa and 25 °C to 1200 kPa and 300°C. Determine the total heat transfer to and work produced by this system.

The information for a solar PV system is given below:Number of PV modules: 5The number of PV cells in one PV module: 36Area of each PV cell = 225 cm2(Select the values as insolation E= 900 w/ m2and efficiency of each module= 16%)If the five PV modules are connected in Series:a. Total output powerb. Total output voltagec. Total output current

22   A power plant has efficiency of 30 % as compared to Fuel Cell power plants. This power plant can be .......................................... a. Geothermal Power Plant b. Wind Power Plant c. Thermal Power Plants d. Biomass Power Plant

4. An incandescent lamp has a tungsten filament whose resistance is 96 ohm at its operating temperature of 2900°C. Calculate the filament resistance when the lamp is disconnected from the electric source under which conditions the temperature is 24°C.