1.
Loads are connected to a voltage source by [ ? ].
Correct Answer
D. Conductors
Explanation
Loads are connected to a voltage source by conductors. Conductors are materials that allow the flow of electric current. In this context, conductors are used to connect the loads, such as batteries, switches, and light bulbs, to the voltage source. Conductors provide a path for the current to flow from the source to the loads, allowing the transfer of electrical energy.
2.
Increasing the voltage applied to a circuit will cause [ ? ].
Correct Answer
A. Current to increase
Explanation
Increasing the voltage applied to a circuit will cause the current to increase. This is because voltage is directly proportional to current according to Ohm's Law. When the voltage is increased, there is a greater potential difference across the circuit, which leads to an increase in the flow of electric charge, or current.
3.
Resistance in a circuit is changed from 10 ohms to 5000 ohms. If the voltage remains the same, the current will [ ? ].
Correct Answer
C. Decrease
Explanation
When the resistance in a circuit is increased, the current flowing through the circuit decreases. This is because according to Ohm's Law, the current is inversely proportional to the resistance. So, if the resistance is increased from 10 ohms to 5000 ohms while keeping the voltage constant, the current will decrease.
4.
In Ohms Law, E stands for [ ? ].
Correct Answer
D. Both B and C are correct
Explanation
In Ohm's Law, E stands for voltage, which is the potential difference between two points in an electrical circuit. It is also known as electromotive force (EMF), which is the force that pushes electrons through a conductor. Both options B and C, voltage and electromotive force, are correct explanations for the letter E in Ohm's Law.
5.
Four light bulbs are connected in a parallel circuit. When another bulb is connected in parallel with the other bulbs, [ ? ].
Correct Answer
B. Current draw will increase
Explanation
When another bulb is connected in parallel with the other bulbs in a parallel circuit, the total resistance of the circuit decreases. According to Ohm's Law (V = IR), when the resistance decreases, the current (I) flowing through the circuit will increase, given that the voltage (V) remains constant. Therefore, the correct answer is that the current draw will increase.
6.
Which of the following items is used to measure angles?
Correct Answer
A. A protractor
Explanation
A protractor is a tool used to measure angles. It consists of a semicircular or circular disc with markings in degrees or radians. The user places the protractor on the vertex of the angle and aligns one of the arms with one side of the angle. The measurement of the angle can then be read from the markings on the protractor. A lever is a simple machine used to lift or move objects, a tachometer is used to measure the rotational speed of a shaft, and a gear is a mechanical device used to transmit motion or power. Therefore, none of these items are used to measure angles.
7.
A properly soldered connection will appear_______
Correct Answer
A. Shiny
Explanation
A properly soldered connection will appear shiny because when soldering, a flux is used to clean the surface of the metal and remove any oxidation. This allows the solder to flow smoothly and create a strong bond between the two surfaces being joined. The shiny appearance indicates that the solder has adhered well to the metal and that the connection is secure.
8.
Which electronic component can store charge?
Correct Answer
D. A capacitor
Explanation
A capacitor is an electronic component that can store charge. It consists of two conductive plates separated by an insulating material called a dielectric. When a voltage is applied across the plates, the capacitor stores electrical energy in the form of charge on its plates. This stored charge can be released later when needed. Capacitors are commonly used in electronic circuits for various purposes such as energy storage, filtering, and coupling signals.
9.
Most 12 V car batteries are made up of eight individual cells connected in series. What is the voltage of each cell in a car battery?
Correct Answer
A. 1.5 V
Explanation
The voltage of each cell in a car battery is 1.5 V. This is because most car batteries are made up of eight individual cells connected in series, which means that the total voltage of the battery is the sum of the voltages of each individual cell. Since the total voltage of a car battery is 12 V, and there are eight cells, each cell must have a voltage of 1.5 V.
10.
What is the frequency of the alternating voltage and current typically used in the United States?
Correct Answer
C. 60 hz
Explanation
The frequency of the alternating voltage and current typically used in the United States is 60 Hz. This means that the direction of the current changes 60 times per second. The standard frequency of 60 Hz is used in most electrical power systems in North America, including the United States.
11.
What is the voltage across the load R and the current through R when the switch is open in the following circuit?
Correct Answer
D. The current is 0 A; the voltage is 0 V.
12.
An AA battery produces a potential difference of 1.5 V. Four AA batteries are placed in series to power a portable FM radio. What is the total voltage of the radio?
Correct Answer
D. 6.0 V
Explanation
When batteries are placed in series, the total voltage is equal to the sum of the individual voltages. Since each AA battery produces a potential difference of 1.5 V, and there are four batteries in series, the total voltage of the radio is 1.5 V + 1.5 V + 1.5 V + 1.5 V = 6.0 V.
13.
Two 8-ohm speakers are connected in parallel to an amplifier with a 24-volt output. What is the voltage across each speaker?
Correct Answer
D. 24 volts
Explanation
When two speakers are connected in parallel, the total resistance decreases. In this case, since both speakers have a resistance of 8 ohms, the total resistance becomes 4 ohms. According to Ohm's law, V = I * R, where V is the voltage, I is the current, and R is the resistance. Since the voltage across the amplifier is 24 volts, and the total resistance is 4 ohms, the current flowing through the circuit is 24/4 = 6 amps. Since the speakers are connected in parallel, the voltage across each speaker is the same as the total voltage, which is 24 volts.
14.
A current meter is connected to a circuit as shown. What does the current meter read?
Correct Answer
B. 4.5 amperes
Explanation
The current meter is connected in series with a 9-ohm resistor and a 3-ohm resistor. According to Ohm's Law, the current flowing through a circuit is equal to the voltage divided by the total resistance. In this case, the voltage is 13.5 volts (the sum of the voltages across the two resistors) and the total resistance is 12 ohms (the sum of the resistances of the two resistors). Therefore, the current flowing through the circuit is 13.5 volts divided by 12 ohms, which equals 1.125 amperes. Since the current meter is connected in series with the circuit, it will read the same current as the circuit, which is 1.125 amperes.
15.
Which mechanical components are typically used between a wheel and an axle to reduce friction?
Correct Answer
C. Bearings
Explanation
Bearings are typically used between a wheel and an axle to reduce friction. Bearings are mechanical components that allow smooth rotation between two parts, such as a wheel and an axle. They consist of a set of balls or rollers that are enclosed in a ring, reducing the contact area and enabling the parts to move with minimal friction. By using bearings, the friction between the wheel and axle is minimized, allowing for more efficient and smoother rotation.
16.
A block of steel has a density of 0.29 pounds per cubic inch. If the block has dimensions of 1 inch by 1 inch by 3 inches, what is its weight?
Correct Answer
C. 0.87 pounds
Explanation
The weight of an object can be calculated by multiplying its volume by its density. In this case, the volume of the block is 1 inch by 1 inch by 3 inches, which equals 3 cubic inches. Multiplying the volume by the density of 0.29 pounds per cubic inch gives us a weight of 0.87 pounds.
17.
In the diagram shown above, the spring is very stiff and can be stretched 1 inch by a pulling force of 100 pounds. How much force must be applied to the block in order to move the box 3.5 inches to the left?
Correct Answer
C. 350 pounds
Explanation
The spring is very stiff and can be stretched 1 inch by a pulling force of 100 pounds. Since the box needs to be moved 3.5 inches to the left, the force required would be 3.5 times the force required to stretch the spring by 1 inch. Therefore, the force required to move the box 3.5 inches to the left would be 3.5 times 100 pounds, which is equal to 350 pounds.