# Types of Heat Transfer: Radiation

#### Academic Questions in PhysicsPlease check out our Test Your Knowledge page to see all Questions and Answers The rate of change of momentum is proportional to the applied force and will take place in the direction of that force. The above statement is attributed to _____. A. Albert Einstein B. Isaac Newton C. Galileo Galilei D. Neils Bohr E. Ernest Rutherford F. Marie Curie The Law of Inertia is also referred to as _____. A. 1st Law of Thermodynamics B. 2nd Law of Thermodynamics C. 3rd Law of Thermodynamics D. Newton's 1st Law of Motion E. Newton's 2nd Law of Motion F. Newton's 3rd Law of Motion The process whereby the velocity of an object increases and decreases over a period of time is best associated with the term _____. A. Speed B. Velocity C. Momentum D. Constant Velocity E. Acceleration F. Average Velocity The rate of motion is best referred to as _____. A. Speed B. Velocity C. Momentum D. Inertia E. Acceleration F. Constant Velocity Consider this expression below: A body X exerts a force FX on another body Y. In return, body Y exert a force FY back on body X. The forces FX and FY are equal in magnitude but opposite in direction. Putting the above expression into equation: FX = -FY Where FX is the action force FY is the reaction Force The above expression relates to _____. A. Theory of Force B. Force Postulate C. Einstein's proposal on Relativity D. Newton's 1st law of motion E. Newton's 2nd law of motion F. Newton's 3rd law of motion The tendency of a body to remain in a state of rest or in uniform motion is referred to as _____. A. Tension B. Uniform acceleration C. Constant acceleration D. Deceleration E. Inertia F. Velocity A change in the position of an object with reference to time is best described as _____. A. Momentum B. Displacement C. Velocity D. Acceleration E. Direction F. Motion The saying 'what goes up on earth must come down' can be best attributed to _____. A. Force B. Motion C. Mass D. Acceleration E. Average velocity F. Constant velocity The term radiate in English mean to “to spread out from a central point”. For instance, the light from the sun radiates to the earth. Also, a lighted bulb will radiate its light in a dark room.

The term radiation (heat radiation) can simply be defined as the transfer of heat in the form of electromagnetic waves.

Note: Whenever heat is transferred via radiation, a contact surface will not be required between the heat source and the object being heated. In this case, the heat is transmitted through space.

One reason why some people put out their bulbs before they go out is to simply conserve energy. Leaving on the bulb will bring an extra heat into the room where it’s present.

Consider the points below regarding radiation through a lighted bulb:

• A bulb will possess a large amount of heat energy if left "switched on" for a long period of time. (Recall that a bulb converts electrical energy to light and heat energy).
• Since energy cannot be lost, the heat energy from the bulb will be radiated around the room where it’s present. The energy transfer goes thus:
###### Electrical Energy >> Light Energy >> Heat Energy

This process of heat transfer from the bulb to the room is a concept of radiation.

Note: In radiation, the heat energy is transferred by electromagnetic waves. In fact, the heat energy which the earth receives from the sun is as a result of electromagnetic waves travelling through space.

The image below shows how heat is radiated to earth from the sun's solar energy: All objects (televisions, phones, phones, computer and any other object) radiate energy in the form of electromagnetic waves. The rate at which this energy is released is directly proportional to the Kelvin temperature (T) raised to the fourth power.

The hotter an object is, the more its ability to radiate heat energy.

The radiated energy is a collection of a range of wavelength referred to as emission spectrum.

The wavelengths within the spectra of the emitted radiation will decrease when the temperature of an object increases; and as a result, hotter objects will usually emit a shorter wavelength at a higher frequency. Alfred Ajibola is a Medical Biochemist, a passionate Academician with over 7 years of experience, a Versatile Writer, a Web Developer, a Cisco Certified Network Associate and a Cisco CyberOps Associate.

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