Free ASVAB Practice Tests

Unlike curved mirrors that operate on the principle of reflection, lenses utilize refraction. A convex lens is thicker in the middle than on the edges and converges light while a concave lens is thicker on the edges than in the middle and diffuses light. A common use for curved lenses is in eye glasses where a convex lens is used to correct farsightedness and a concave lens is used to correct nearsightedness.

Files consist of diagonal rows of fine teeth and are used for fine finishing work to smooth, polish, or shape objects. Rasps are files with larger teeth that are used for coarse finishing work. Both files and rasps are designed to be inserted into detachable handles.

The stoichiometric ratio defines the proper ratio of air to fuel necessary so that an engine burns all fuel with no excess air. For gasoline fuel, the stoichiometric ratio is about 14.7:1 or for every one gram of fuel, 14.7 grams of air are required. Too much air results in a lean air-fuel mixture that burns more slowly and hotter while too much fuel results in a rich mixture that burns quicker and cooler.

To solve this equation, repeatedly do the same thing to both sides of the equation until the variable is isolated on one side of the equal sign and the answer on the other.

-5z - 3 = \( \frac{z}{-3} \)
-3 x (-5z - 3) = z
(-3 x -5z) + (-3 x -3) = z
15z + 9 = z
15z + 9 - z = 0
15z - z = -9
14z = -9
z = \( \frac{-9}{14} \)
z = -\(\frac{9}{14}\)

Ohm's law specifies the relationship between voltage (V), current (I), and resistance (R) in an electrical circuit: V = IR.

Solved for resistance, R = \( \frac{V}{I} \) = \( \frac{40}{2} \) = 20 Ω

The purpose of a capacitor is to retain electric charge and it will do so even after its input voltage is removed. After the input voltage is removed, the capacitor will slowly discharge but, depending on the size and characteristics of the capacitor, discharging could take from a few minutes to a few years. So, it's never safe to touch a capacitor with your hands and you should make sure to discharge any capacitors in a circuit before working on it using an appropriately high-wattage resistor or a capacitor discharge tool.

The respiratory system manages respiration which is the process by which blood cells absorb oxygen and eliminate carbon dioxide.

Heat is always transferred from warmer to cooler environments and conduction is the simplest way this transfer can occur. It is accomplished through direct contact between materials and materials like metals that transfer heat efficiently are called conductors while those that conduct heat poorly, such as plastic, are called insulators.

The heart is the organ that drives the circulatory system. In humans, it consists of four chambers with two that collect blood called atria and two that pump blood called ventricles. The heart's valves prevent blood pumped out of the ventricles from flowing back into the heart.