Energy and Waves Practice Flashcards

A comprehensive set of flashcards covering energy stores, transfers, calculations, resources, and the properties and applications of waves and the electromagnetic spectrum.

What are the seven ways energy may be stored?

Energy may be stored as kinetic, gravitational potential, chemical, elastic (strain), nuclear, electrostatic, and internal (thermal).

What are the four primary methods by which energy is transferred between stores?

Energy is transferred by forces (mechanical work done), electrical currents (electrical work done), heating, and by electromagnetic, sound, and other waves.

What is the principle of conservation of energy?

The principle states that energy cannot be created or destroyed, only transferred between stores.

What is the formula for kinetic energy?

$$E_k = \frac{1}{2}mv^2$$

What is the formula for the change in gravitational potential energy?

$$\Delta E_p = mg\Delta h$$

What is the relationship between work done and energy transferred?

Mechanical or electrical work done is equal to the energy transferred.

What is the equation for mechanical work?

$$W = Fd = \Delta E$$

Which energy resources do not have the Sun as their original source?

Geothermal, nuclear, and tidal resources.

How is energy released in the Sun?

Energy is released by nuclear fusion.

How is energy released in nuclear reactors?

Energy is released by nuclear fission.

How is power defined and what are its equations?

Power is work done per unit of time or energy transferred per unit of time; $P = \frac{W}{t}$ or $P = \frac{E}{t}$.

What energy transfer occurs in cells and batteries?

They transfer chemical energy into electrical energy.

What energy transfer occurs in generators?

They transfer kinetic energy into electrical energy.

What energy transfer occurs in electric motors?

They transfer electrical energy into kinetic energy.

Do waves transfer matter?

No, waves transfer energy without transferring matter.

What are the features used to describe a wave?

Wavelength, frequency, crest (peak), trough, amplitude, and wave speed.

What leads to the refraction of a wave?

Refraction is due to a change of speed.

What is the equation for wave speed?

$$v = f\lambda$$

What is the definition of a transverse wave and what are some examples?

For a transverse wave, the direction of vibration is at right angles to the direction of propagation; examples include electromagnetic radiation, water waves, and seismic S-waves (secondary).

What is the definition of a longitudinal wave and what are some examples?

For a longitudinal wave, the direction of vibration is parallel to the direction of propagation; examples include sound waves and seismic P-waves (primary).

What is the speed of electromagnetic waves in a vacuum?

$$3.0 \times 10^8\,\text{m/s}$$

What are the applications for radio waves and microwaves?

Radio waves are used for radio and television transmissions and radar; microwaves are used for satellite television, mobile (cell) phones, and microwave ovens.

What are the applications for infrared and visible light?

Infrared is used for remote controllers for televisions and thermal imaging; visible light is used for vision and photography.

What are the applications for ultraviolet, X-rays, and gamma rays?

Ultraviolet is used for detecting fake bank notes; X-rays are used for medical and security scanning; gamma rays are used for the detection and treatment of cancer.

What are the harmful effects of excessive exposure to ultraviolet radiation?

Damage to surface cells and eyes, leading to skin cancer and eye conditions.

What are the harmful effects of excessive exposure to X-rays and gamma rays?

Mutation or damage to cells in the body.