Physics

Types of Heat Transfer: Radiation

len Alfred Ajibola - Thu, 26th December, 2019 @ 17:24: PM

Topics in Physics

Derived Units: Similarities and Differences with Fundamental Units Gravity: Interesting facts on Gravity Relative Density of Substances and Specific Gravity Types of Heat Transfer: Conduction Types of Heat Transfer: Convection Types of Heat Transfer: Radiation Physics Scheme of Work, SS1, First Term Physics Scheme of Work, SS1, Second Term Physics Scheme of Work, SS1, Third Term Velocity and Acceleration Newton's Laws of Motion Importance of Gravity What is Density? Density of various Substances Concepts of Force and Motion Motion and Speed Concept of Heat Transfer Concepts of Heat and Temperature Gravity: What is Gravity? Zeroth Law of Thermodynamics - Thermal Equilibrium Fundamental Quantities and Units in Physics


Academic Questions in Physics

Please check out our Test Your Knowledge page to see all Questions and Answers

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

We have _____ laws of Thermodynamics.

  • A. 1
  • B. 2
  • C. 3
  • D. 4
  • E. 5
  • D. 6

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Heat Transfer - Radiation:

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.

Please read on Heat Transfer through Convection here.

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.

Please read on the Concept of Heat and Temperature here.

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.

Please read on the Concept of Heat Transfer here.

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.

Please read on Heat Transfer through Conduction here.

The image below shows how heat is radiated to earth from the sun's solar energy:

Heat Transfer by Radiation - Len Academy

Please read on the Solar System here.

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.

Radiation rate = k•T4

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.

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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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Amazing facts in Physics

Image Credit: Ball and Roller Store

Glass Balls actually bounce higher than Rubber Balls

Every planet has its own unique gravitational force, for instance, Mars has a gravity of 3.711 m/s2 while earth’s gravitational force is 9.807m/s2Please read on gravity here

When two metals are put together in space, they will stick together as if they are welded. This phenomenon is called cold welding

The fastest animal on land is Cheetah. It can reach a maximum speed of about 113km per hour.
Please read on motion, speed, velocity and acceeration here


NOTABLE POINTS IN Physics

The Classical Mechanics (Laws of Motion) is a fundamental part of Physics.

Below are the Newton's Laws of Motion:

An object at rest will continue in its state of rest; while an object in uniform motion will continue in a straight line, unless an external force acts on it.

Newton's First Law of Motion.

Please read on Motion and Speed here.

The rate of change of momemtum is proportional to the applied force and will take place in the direction of that force.

Newton's Second Law of Motion.

To every action, there is an equal and opposite reaction.

Newton's Third Law of Motion.

Please read on Newton's Laws of Motion here.

The study of Thermodynamics revolves around the relationship between heat, temperature, energy and mechanical work; and these can be summarised under the 4 laws of Thermodynamics (Numbered zero through three).

You can read on the Concepts of Heat and Temperature here.

Below are the 4 laws of thermodynamics:

Zeroth law of thermodynamics – If two thermodynamic systems are each in thermal equilibrium with a third, then they are in thermal equilibrium with each other.

Please read on the Zeroth Law of Thermodynamics here.

1st law of thermodynamics – Energy can neither be created nor destroyed but can be changed from one form to another.

You can read on the Food Chain here.

2nd law of thermodynamics – The entropy of an isolated system not in equilibrium will tend to increase over time, approaching a maximum value at equilibrium.

3rd law of thermodynamics – As temperature approaches absolute zero, the entropy of a system approaches a constant minimum.

Fuses are present in many electrical devices. They are basically 🔥 fire-breakers 🔥

If there is a power surge, the fuse will break, preventing damage to the electrical devices. It will also prevent the incidence of 🔥 fire🔥 on/from such device.

Physics is one of the core sciences.

Physics is defined the scientific study of matter and the movement of matter through the space and time of the universe.

Understanding the basic and fundamental concepts of physics will help you better comprehend this subject. Below are some of the concepts:

  1. The Laws of Motion (Classical Mechanics)
  2. Electromagnetism
  3. Relativity
  4. Thermodynamics

Please read on the basic introduction of the above physics concept here