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Sample Practice Test Questions
A diode to an electronic circuit is like a _______________ to a city?
one-way street
A diode allows current to pass easily in one direction and blocks current in the other direction.
Which of the following is not a characteristic of direct current?
an example power source is a generator
Direct current flows in only one direction in a circuit, from the negative terminal of the voltage source to the positive. A common source of DC is a battery. In contrast to the constant one-way flow of direct current, alternating current changes direction many times each second. Electricity is delivered from power stations to customers as AC because it provides a more efficient way to transport electricity over long distances.
In the foood chain, producers serve as a food source for other organisms. Typical producers are plants that can make their own food through photosynthesis and certain bacteria that are capable of converting inorganic substances into food through:
chemosynthesis
Producers (autotrophs) serve as a food source for other organisms. Typical producers are plants that can make their own food through photosynthesis and certain bacteria that are capable of converting inorganic substances into food through chemosynthesis
This circuit component symbol represents a(n):
fuse
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 green box weighs 10 lbs. and a 35 lbs. weight is placed 3 ft. from the fulcrum at the blue arrow. How far from the fulcrum would the green box need to be placed to balance the lever?
To balance this lever the torques on each side of the fulcrum must be equal. Torque is weight x distance from the fulcrum so the equation for equilibrium is:
Rada = Rbdb
where a represents the left side of the fulcrum and b the right, R is resistance (weight) and d is the distance from the fulcrum.Solving for da, our missing value, and plugging in our variables yields:
da = \( \frac{R_bd_b}{R_a} \) = \( \frac{35 lbs. \times 3 ft.}{10 lbs.} \) = \( \frac{105 ft⋅lb}{10 lbs.} \) = 10.5 ft.
A fixed pulley is useful for which of the following?
changing the direction of the input force
A fixed pulley is used to change the direction of a force and does not multiply the force applied. As such, it has a mechanical advantage of one. The benefit of a fixed pulley is that it can allow the force to be applied at a more convenient angle, for example, pulling downward or horizontally to lift an object instead of upward.
What is 7\( \sqrt{4} \) x 6\( \sqrt{4} \)?
To multiply terms with radicals, multiply the coefficients and radicands separately:
7\( \sqrt{4} \) x 6\( \sqrt{4} \)
(7 x 6)\( \sqrt{4 \times 4} \)
42\( \sqrt{16} \)
Now we need to simplify the radical:
42\( \sqrt{16} \)
42\( \sqrt{4^2} \)
(42)(4)
168
The ozone layer is in which of Earth's atmospheric layers?
stratosphere
The stratosphere is just above the troposphere and is stratified in temperature with warmer layers higher and cooler layers closer to Earth. This increase in temperature is a result of absorption of the Sun's radiation by the ozone layer.
If angle a = 53° and angle b = 27° what is the length of angle d?
An exterior angle of a triangle is equal to the sum of the two interior angles that are opposite:
d° = b° + c°
To find angle c, remember that the sum of the interior angles of a triangle is 180°:
180° = a° + b° + c°
c° = 180° - a° - b°
c° = 180° - 53° - 27° = 100°
So, d° = 27° + 100° = 127°
A shortcut to get this answer is to remember that angles around a line add up to 180°:
a° + d° = 180°
d° = 180° - a°
d° = 180° - 53° = 127°