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This video explains the angles of elevation and depression.

When electromagnetic radiation is absorbed by a material the energy it carries has to go somewhere. When lower energy waves, like radio and infrared waves, are absorbed there can be an increase in temperature of the absorbing material. Higher energy waves, like x-ray and gamma waves, can actually permanently damage or change materials. Learn about the different types of electromagnetic waves and how their energies can influence their effects on objects.

There are many different processes and phenomena that emit electromagnetic radiation. Humans have taken advantage of many of these processes to develop technologies that use electromagnetic radiation.

The beauty of a coral reef, the warm radiance of sunshine, the sting of sunburn, the X-ray revealing a broken bone, even microwave popcorn—all are brought to us by electromagnetic waves. The list of the various types of electromagnetic waves, ranging from radio transmission waves to nuclear gamma-ray (γ-ray) emissions, is interesting in itself.

Even more intriguing is that all of these different phenomena are manifestations of the same thing—electromagnetic waves (see Figure 15.1). What are electromagnetic waves? How are they created, and how do they travel? How can we understand their widely varying properties? What is the relationship between electric and magnetic effects? These and other questions will be explored.

Photoelectric materials emit electrons when they absorb light of a high-enough frequency.

An online application to test your knowledge of evaluating trigonometric functions of special angles.

By the end of this unit you will be able to:

• Define and use the trigonometric ratios of cosθ, sinθ and tanθ.
• Calculate the trigonometric ratios in each quadrant of the Cartesian plane.
• Calculate the value of expressions containing trigonometric ratios.

Outcomes

By the end of this course you will be able to:

• Define and use the trigonometric ratios of  cosθ,  sinθ, and  tanθ.
• Calculate the value of expressions containing trigonometric ratios with a calculator.
• Calculate the value of expressions containing trigonometric ratios without a calculator.
• Work with trigonometric tables.
• Solve problems in 2 dimensions involving angles of elevation and depression

Short tutorial on trigonometry

An explanation of wave interference and solution of a few examples to find the value of the total wave when two wave pulses overlap