The earth receives solar energy at the rate of 1000 `Wm^(-2)`. A solar water heater of area `4m^(2)` absorbs 60% of incident energy. Find the time required to rise the temperature of 100L of water by `40^(@)C`

Earth receives solar energy at a rate of 1000 Wm^(-2) . A solar water heater of area 2m^(2) absorbs 50% of incident energy. Find the time required to raise the temperature of 50 litres of water by 50^(@)C . (C_(W)= 4180 J kg^(-1) K^(-1))

How much heat energy is necessary to raise the temperature of 2.5 kg of water from 20 ^@ C " to " 100^@C ?

The earth receives solar energy at the rate of 2 cal Cm^(-2) per minute. Assuming theradiation tobeblack body in character, estimate the surface temperature of the sun. Given that sigma =5.67 xx10^(-8) Wm^(-2)K^(-4) and angular diameter of the sun =32 minute of arc.

In a solar water heater, energy from the Sun is gathered by water that circulates through tubes in a rooftop collector. The solar radiation enters the collector through a transparent cover and warms the water in the tubes, this water is pumped into a holding tank. Assume that the efficiency of the overally system is 25% ( that is, 80% of the incident solar energy is lost from the system ). What collector area is necessary to raise the temperature of 200L of water in the tank from 20^(@)C to 40^(@) in 1.0 h when the intensity of incident sunlight is 750 W // m^(2) ?

A hollow spherical conducting sheel of inner radius R_(1) = 0.25 m and outer radius R_(2) = 0.50 m is placed inside a heat reservoir of temperature T_(0) = 1000^(@)C . The shell is initially filled with water at 0^(@)C . The thermal conductivity of the material is k =(10^(2))/(4pi) W//m-K and its heat capacity is negligible. The time required to raise the temperature of water to 100^(@)C is 1100 ln.(10)/(9) sec . Find K . Take specific heat of water s = 4.2 kJ//kg.^(@)C , density of water d_(w) = 1000 kg//m^(3) pi = (22)/(7)

At a place, the solar energy incident in one second is 640 J, on an area of one square metre. Assuming that all the solar energy is absorbed by 10 kg water, incident on its surface of area 400 cm^(2) . How much time will it take to raise its temperature by 70^(@)C ? (specific heat capacity of water is 4.2 J g^(-1) .^(@)C^(-1) )

A heating coil of 2000 W is immersed in water . How much time will it take in raising the temperature of 1 L of water from 4^(@) C "to" 100^(@) C ? Only 80% of the thermal energy produced is used in raising the temperature of water.

How much solar energy will be received by 1 m^(2) area in one hour if the solar constant be 1.4 kW//m^(2) ?

The heater coil of an elecric kettle is rated at 2000W,200V, How much time will in take is rasing the temperature of 1 litres of water from 20^(@)C to 100^(@)C . Assuming that only 80% of the total heat energy produced by the heater coil is used in raising the temperature of water. Density of water heater coil is used in raising the temperture of water. density of water = 1g cm^(-3) and specific heat of water = 1 "cal" g^(-1) .^(@)C^(-1) .