Tag: physics

Questions Related to physics

A solar water heater cannot be used to get hot water on:

  1. a sunny day.

  2. a cloudy day.

  3. hot day.

  4. windy day.


Correct Option: B
Explanation:

Solar devices are dependent on the sunlight for the generation of electricity. For the solar device to work efficiently, sunlight with good intensity should be available. Sunlight is weak during cloudy and rainy days. 

Which of the following devices convert solar light to electricity?

  1. Wind mills

  2. Turbines

  3. Thermostat

  4. Solar Panels


Correct Option: D
Explanation:

Solar panels are used to convert light (from solar energy) into electricity.

Wind mills harness wind energy to generate electricity.
Turbines are used in dams, which help in utilizing the kinetic energy of water in rivers.
Thermostat is a device used for maintenance of constant temperature. It is not used for energy production.  

Which ones are uses of solar panels?

  1. used in satellites and mars probe

  2. used in traffic signals

  3. used in calculators and toys

  4. All of the above


Correct Option: D
Explanation:

Solar panels can be used in calculators and battery operated toys, in satellites and Mars probes to provide them with energy to function in outer space by using the Sun's rays, can be used in traffic signals etc.

State whether the given statement is True or False :
Solar panels can produce electricity throughout the year. 
  1. True

  2. False


Correct Option: B
Explanation:

Solar panels are dependent on the sunlight for the generation of electricity. For the solar panels to work efficiently, sunlight with good intensity should be available to fall on the panels. Sunlight is weak during cloudy and rainy days. Hence, solar panels cannot produce energy throughout the year.

What is estimation of solar constant?

  1. 1.4 kW per square meter

  2. 1.4 W per square meter

  3. 1.6 kW per square meter

  4. 1.4 kW per square centimeter


Correct Option: A
Explanation:

Solar constant is defined as the mean amount of the solar energy received by the Earth's atmosphere, per unit of the area, during the time when the Earth is at the mean distance from the Sun. Solar constant equals to 1388 watts per square meter.

Which of the following element is used in making solar cells?

  1. Gold

  2. Carbon

  3. Silicon

  4. Silver


Correct Option: C
Explanation:

Solar cells are devices that converts Sun's radiation energy into electricity. Solar cells contains a semiconductor. Silicon is a good semiconductor that can be used for the production of solar cells.

A solar water heater cannot be used to get hot water on

  1. a sunny day

  2. a cloudy day

  3. a hot day

  4. a windy day


Correct Option: B
Explanation:

A solar water heater cannot be used to get hot water on a cloudy day as there is no Sun which is necessary for the working of solar water heater.

In parabolic solar cooker, the container of cooking is placed at the :

  1. Centre of curvature of mirror

  2. Focal point of the mirror

  3. Can be placed anywhere

  4. None of these


Correct Option: B
Explanation:

In parabolic solar cooker, the container of cooking is placed at the focal point of mirror so that all rays that are falling on solar cooker can converge to one point and produce large amount of heat energy.

The solar device used in traffic signal light, works on which of  the following principle?

  1. Conservation of momentum

  2. Doppler effect

  3. Photovoltaic effect

  4. Electromagnetic induction


Correct Option: C
Explanation:

The device used in traffic signal lights is Solar traffic light. are signalling devices powered by solar panels positioned at road intersections, pedestrian crossings and other locations to control the flows of traffic. 


Most solar traffic lights use LED lamps inside. These lamps work on the principle of Photovoltaic effect to work.
Hence correct answer is option C.