Tag: solar power

Questions Related to solar power

In order to absorb more heat, the outer surface of copper tube of solar water heater is coloured with :

physics solar equipment production of electricity from solar energy solar power alternate sources of energy solar power plant solar energy and its applications renewable and non-renewable resources renewable and non-renewable sources of energy generation of electricity

  1. Red

  2. Yellow

  3. Black

  4. Green

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Correct Option: C
Explanation:

Among all colour black is the best absorber for heat  so outer surface of copper tube is coloured with black.

Two identical immersion heaters are to be used to heat water, in a large container. Which one of the following arrangement would heat the water faster :
Give reasons for your answer.

physics solar equipment production of electricity from solar energy solar power alternate sources of energy solar power plant solar energy and its applications renewable and non-renewable resources renewable and non-renewable sources of energy generation of electricity

  1. Connecting the heaters in series with the main supply,

  2. Connecting the heaters in parallel with the main supply,

  3. Connecting the heaters in series and parallel with the main supply,

  4. None of the above

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Correct Option: A

Which of the following is used in solar cooker to harvest the solar energy?

physics solar equipment production of electricity from solar energy solar power alternate sources of energy solar power plant solar energy and its applications renewable and non-renewable resources renewable and non-renewable sources of energy generation of electricity

  1. Solar panels

  2. Silicon cell

  3. Mirrors

  4. Glass lid

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Correct Option: B

In geothermal plants steam is raised by pumping water upto the layer of magma.                           .......................

physics energy : forms and sources production of electricity from solar energy solar equipment solar power renewable and non-renewable resources renewable and non-renewable sources of energy

  1. True

  2. False

  3. Ambiguous

  4. Data insufficient

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Correct Option: A
Explanation:

The most common way of capturing the energy from geothermal sources is to tap into naturally occurring 'hydrothermal convection' systems, where cooler water seeps into Earth's crust, is heated up, and then rises to the surface. Once this heated water is forced to the surface, it is a relatively simple matter to capture that steam and use it to drive electric generators. Geothermal power plants drill their own holes into the rock to more effectively capture the steam.
Hence, the statement is true.

Relation between constant volume specific heat $(C _v)$ and degree of freedom $(f)$ for a gas is ($R$ is gas constant) 

physics solar equipment solar power plant production of electricity from solar energy solar power solar energy and its applications generation of electricity

  1. $C _v=\dfrac{f}{2} R$

  2. $C _v=fR$

  3. $C _v=\dfrac{f}{R}$

  4. $C _v=\dfrac{R}{f}$

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Correct Option: A
Explanation:

The internal energy of 1 mole of an ideal gas at temperature $T$ , having $f$ degrees of freedom is given by ,

          $U=N _{A}\times(1/2)fk _{B}T=(1/2)fRT$  ......................eq1
where $N _{A}=$Avogadro's number
           $k _{B}=$ Boltzmann's constant
from first law of thermodynamics ,
           $dU=dQ-dW$  ............eq2
At constant volume , $dV=0$ 
hence  $dW=PdV=0$
eq2 becomes , $dU=dQ$
but       $dQ=C _{V}dT$  (for 1 mole of gas)
therefore $dU=C _{V}dT$
or            $C _{V}=dU/dT$
putting the value of $U$ in this equation, we get
                $C _{V}=\frac{d(1/2)fRT}{dT}=\frac{f}{2}R$

Temperature of a gas is $20^o$C and pressure is changed from $1.01\times 10^5$ Pa to $1.165\times 10^5$ Pa. If volume is decreased isothermally by $10\%$. Bulk modulus of gas is?

physics solar equipment solar power plant production of electricity from solar energy solar power solar energy and its applications generation of electricity

  1. $1.55\times 10^5$

  2. $0.155\times 10^5$

  3. $1.4\times 10^5$

  4. $1.01\times 10^5$

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Correct Option: A
Explanation:
$B=-V\dfrac{\Delta P}{\Delta V}$
$=V _0\dfrac{(1.165-1.01)\times 10^5}{0.1\ V}$
$=1.55\times 10^5$

The room heater can maintain only ${16^0}C$ in the room when the temperature outside is -${20^0}C$. It is not warm and comfortable, that is why the electric stove with power of 1 kw is also plugged in.Together these two devices maintain the room temperature of ${22^0}C$. Determine the thermal  power of the heater.

physics solar equipment solar power plant production of electricity from solar energy solar power solar energy and its applications generation of electricity

  1. 3kW

  2. 4 kW

  3. 5kW

  4. 6kW

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Correct Option: C