Answer:
The greenhouse effect is a natural process that warms the Earth’s surface.
Explanation:
Solar radiation heats Earth surface. When solar radiation reaches to Earth a certain level of radiation is being absorbed by Earth and rest of the radiation is being reflected to space. But because of greenhouse gasses (such as water vapour, carbon dioxide, methane, nitrous oxide, ozone and some artificial chemicals such as chlorofluorocarbons) that exist in Earth atmosphere reflected radiation is being absorbed by atmosphere. If greenhouse gasses percentages raises into Earth atmosphere, the more radiation will be absorbed. Therefore, heat level of Earth is going to be raised.
Answer:
1) i. All these technologies use radio waves, including high-frequency microwaves.
ii. Microwave ovens emit in the same frequency band as some wireless Internet devices.
2. B. The earth absorbs visible light and emits radiation with a longer wavelength.
Explanation:
Electromagnetic radiations are generated when there is an interference between electric and magnetic fields traveling at right angles to each other. All electromagnetic waves forms a spectrum with respect to their frequency and wavelength. The higher the wavelength, the lower the frequency.
All these waves move with the same and constant speed, but are generated from different sources. From the given applications, X-ray has a high frequency, but low wavelength.
In the second case, infrared waves have longer wavelength than visible light.
Answer:
0.06925 A
18000 J
Explanation:
V = Voltage = 3.8 V
P = Power = 1 W
t = Time = 5 hours
Power is given by
The average current the phone draws from its battery is 0.06925 A
Energy is given
The energy stored in a fully charged battery is 18000 J
The correct answer is convection
In liquids and gases, convection is the most prominent method for the transfer of energy or heat. Convection is caused by the movement of the hotter particles to a region of colder particles takes place. This results in making the whole liquid or gas hot or warm.
Example: The water bubbles in boiling water moves from bottom to the top of the pan to cover the colder water present at the top.
This is because of convection.
Energy = force x distance
600 J = force x 3 m
force = 200 N
Work = force x distance
Work = 200 N x 3 m
Work = 600 J
Therefore work done = energy
