Free ASVAB Practice Tests

Semiconductors have valence shells that are exacly half full and can conduct electricity under some conditions but not others. This property makes them useful for the control of electrical current.

An acid is a substance that gives up positively charged hydrogen ions (H⁺) when dissolved in water. A base (alkaline) gives up negatively charged hydroxide ions (OH^-) when dissolved in water. pH is a scale that measures of how basic or acidic a solution is. Numbered from 0 to 14, solutions with a pH of 7 are neutral, less than 7 are acidic, more than 7 are alkaline.

Connecting the 4 batteries in series multiplies their voltage while keeping their current the same yielding a 60V 15A configuration. Connecting the 4 batteries in parallel multiplies their current while keeping their voltage the same yieleding a 15V 60A configuration. Using a series-parallel connection, 2 batteries can be connected in series and 2 can be connected in parallel resulting in a 30V 30A configuration.

To multiply monomials, multiply the coefficients (the numbers that come before the variables) of each term, add the exponents of like variables, and multiply the different variables together.

(9a)(8ab) + (7a²)(8b)
(9 x 8)(a x a x b) + (7 x 8)(a² x b)
(72)(a¹⁺¹ x b) + (56)(a²b)
72a²b + 56a²b
128a²b

Fuses are thin wires that melt when the current in a circuit exceeds a preset amount. They help prevent short circuits from damaging circuit components when an unusually large current is applied to the circuit, either through component failure or spikes in applied voltage.

The mechanical advantage of a gear train is its gear ratio. The gear ratio (V_r) is the product of the gear ratios between the pairs of meshed gears. Let N represent the number of teeth for each gear:

V_r = \( \frac{N_1}{N_2} \) \( \frac{N_2}{N_3} \) \( \frac{N_3}{N_4} \) ... \( \frac{N_n}{N_{n+1}} \)

In this problem, we have three gears so the equation becomes:

V_r = \( \frac{N_1}{N_2} \) \( \frac{N_2}{N_3} \) = \( \frac{24}{16} \) \( \frac{16}{4} \) = \( \frac{24}{4} \) = 6

Mantle makes up 84% of the Earth's volume and has an average thickness of approximately 1,800 miles (2,900 km). It is dense, hot, and primarily solid although in places it behaves more like a viscous fluid as the plates of the upper mantle and crust gradually "float" along its circumference.

Use PEMDAS (Parentheses, Exponents, Multipy/Divide, Add/Subtract):

2 + (5 + 2) ÷ 5 x 3 - 4²
P: 2 + (7) ÷ 5 x 3 - 4²
E: 2 + 7 ÷ 5 x 3 - 16
MD: 2 + \( \frac{7}{5} \) x 3 - 16
MD: 2 + \( \frac{21}{5} \) - 16
AS: \( \frac{10}{5} \) + \( \frac{21}{5} \) - 16
AS: \( \frac{31}{5} \) - 16
AS: \( \frac{31 - 80}{5} \)
\( \frac{-49}{5} \)
-9\(\frac{4}{5}\)

Resistance is opposition to the flow of current and is measured in ohms (Ω). One ohm is defined as the amount of resistance that will allow one ampere of current to flow if one volt of voltage is applied. As resistance increases, current decreases as resistance and current are inversely proportional.

Blood transfer is limited by the type and Rh factor of the blood. Someone who has Rh-factor negative blood cannot receive blood with a positive type but a person with Rh-factor positive type blood can receive Rh-negative blood. Type O negative blood is the universal donor because it can be given to a person with any blood type. Type AB positive is the universal recipient meaning someone with this blood type can receive any other type of blood.