1.
A 6-volt lead-acid battery has an internal resistance of 0.01 ohm. How much current will flow if the battery has a short circuit?
Correct Answer
B. 600A
Explanation
When a battery has a short circuit, it means that there is a direct connection between its positive and negative terminals, bypassing the internal resistance. In this case, Ohm's Law states that the current flowing through a circuit is equal to the voltage divided by the resistance. Since the internal resistance is 0.01 ohm and the voltage is 6 volts, the current flowing through the short circuit would be 6 volts divided by 0.01 ohm, which equals 600 amperes. Therefore, the correct answer is 600A.
2.
A binary alloy of copper and zinc.
Correct Answer
A. Brass
Explanation
Brass is a binary alloy of copper and zinc. It is a commonly used material due to its desirable properties such as high corrosion resistance, low friction, and excellent electrical conductivity. The addition of zinc to copper gives brass its distinct golden color and enhances its strength and durability. Brass is widely used in various applications, including musical instruments, plumbing fittings, decorative items, and electrical connectors.
3.
The resistance of a conductor when its temperature is increased,
Correct Answer
A. Increases
Explanation
When the temperature of a conductor is increased, the resistance also increases. This is because as the temperature rises, the atoms in the conductor vibrate more vigorously, causing more collisions with the free electrons that carry the electric current. These collisions impede the flow of electrons, resulting in an increase in resistance. Therefore, the resistance of a conductor increases with an increase in temperature.
4.
A voltage source of 20V is applied across the terminals of a 2.5-ohm rheostat. Calculate the powerdissipated in the rheostat?
Correct Answer
A. 160W
Explanation
The power dissipated in a circuit can be calculated using the formula P = V^2 / R, where P is the power, V is the voltage, and R is the resistance. In this case, the voltage across the rheostat is 20V and the resistance is 2.5 ohms. Plugging these values into the formula, we get P = (20^2) / 2.5 = 400 / 2.5 = 160W. Therefore, the power dissipated in the rheostat is 160W.
5.
Unit of electrical pressure is
Correct Answer
A. Volt
Explanation
The unit of electrical pressure is volt. Volt is a measure of the electric potential difference between two points in a circuit. It represents the amount of force or pressure that pushes electric charges to flow through a conductor. The other options, ohm, ampere, and watt, are units of electrical resistance, current, and power respectively, and are not measures of electrical pressure.
6.
Two resistors of resistances 5 ohms and 7 ohms are connected in series across a 60-volt source. What is the power absorbed in the 5-ohm resistor?
Correct Answer
C. 125 watts
Explanation
You have two resistors, one with 5 ohms of resistance and the other with 7 ohms. They are connected one after the other in a line (series) and hooked up to a 60-volt power source. Imagine electricity flowing through this setup like water through a pipe. When electricity flows through a resistor, it loses some energy and that energy turns into heat. We want to know how much heat (power) the 5-ohm resistor is making.
To figure this out, first, we need to find out how much of the 60 volts from the power source is used up by the 5-ohm resistor. We find this using a rule called the voltage divider rule, which tells us that out of the 60 volts, the 5-ohm resistor uses 25 volts. Now, we use a simple formula to find the power (heat) produced by the 5-ohm resistor. The formula is: Power (in watts) = Voltage^2 / Resistance. Plug in the values: Power = (25 volts)^2 / 5 ohms = 625 / 5 = 125 watts. So, the 5-ohm resistor is producing 125 watts of heat. That's the answer: 125 watts.
7.
When using ohms law, E divided by I would solve for
Correct Answer
A. Resistance
Explanation
When using Ohm's law, the equation E (voltage) divided by I (current) solves for resistance. Ohm's law states that the voltage across a conductor is directly proportional to the current passing through it, and the constant of proportionality is the resistance. Therefore, by dividing the voltage by the current, we can determine the resistance of the conductor.
8.
In resistance color coding, red color is assigned to a
value
Correct Answer
B. 2
Explanation
In resistance color coding, the color red is assigned to the value 2.
9.
An electric iron takes 3 ½ amps. If the heating element has a resistance of 40 ohms, what is its power
consumption?
Correct Answer
B. 0.49 kW
10.
Another name for a secondary cell.
Correct Answer
B. Storage cell
Explanation
A storage cell is another name for a secondary cell. Unlike disposable cells, which are designed for single use and cannot be recharged, secondary cells can be recharged and reused multiple times. Therefore, the term "storage cell" refers to a type of battery that can store and release electrical energy repeatedly.
11.
Two resistances of 8 and 10 ohms respectively are connected in parallel and take a total current of 9 A.
What is the current flowing in the 8-ohm resistance?
Correct Answer
A. 5 A
Explanation
When resistances are connected in parallel, the total current is divided between them. The current flowing through each resistance is inversely proportional to their values. In this case, the resistance of 8 ohms is smaller than the resistance of 10 ohms, so it will have a larger current flowing through it. Since the total current is 9 A, the current flowing through the 8-ohm resistance can be calculated using the formula: current = total current / (total resistance / individual resistance). Plugging in the values, we get 9 A / (18 ohms / 8 ohms) = 9 A / (9/4) = 9 A * (4/9) = 4 A. Therefore, the current flowing in the 8-ohm resistance is 4 A.
12.
What is the resistance must be connected across a
4-ohm resistor in order to give an equivalent
resistance of 3 ohms?
Correct Answer
D. None of these
Explanation
In order to find the resistance that must be connected across a 4-ohm resistor to give an equivalent resistance of 3 ohms, we need to use the formula for resistors in parallel. The formula is 1/Req = 1/R1 + 1/R2, where Req is the equivalent resistance and R1 and R2 are the individual resistances. Rearranging the formula to solve for R2, we get R2 = (1/Req - 1/R1)^-1. Plugging in the given values, R1 = 4 ohms and Req = 3 ohms, we get R2 = (1/3 - 1/4)^-1 = (4/12 - 3/12)^-1 = (1/12)^-1 = 12 ohms. Therefore, the correct answer is 12 ohms.
13.
How is voltmeter connected in a circuit?
Correct Answer
C. Connect in series across the load
Explanation
A voltmeter is connected in series across the load in a circuit. This means that the voltmeter is connected in such a way that it is in line with the load, allowing it to measure the voltage drop across the load. By connecting the voltmeter in series, it becomes a part of the circuit and can accurately measure the voltage without affecting the flow of current in the circuit.
14.
Component of an atom that doesn’t have any electrical charge.
Correct Answer
C. Neutron
Explanation
A neutron is a component of an atom that doesn't have any electrical charge. It is located in the nucleus of the atom along with protons, which have a positive charge. Electrons, on the other hand, have a negative charge and orbit around the nucleus. Neutrons play a crucial role in determining the stability and mass of an atom.
15.
A lead-acid cell is constructed in multiple for the
purpose of ______.
Correct Answer
D. All of these
Explanation
A lead-acid cell is constructed in multiple for the purpose of increasing the emf of the cell, increasing the capacity of the cell, and increasing the internal resistance of the cell.
16.
A measuring instrument used to measure the diameter of circular wires in mills.
Correct Answer
C. Wire gauge
Explanation
A wire gauge is a measuring instrument specifically designed to measure the diameter of circular wires in mills. It is commonly used in various industries, such as electrical and jewelry, to ensure accurate sizing and compatibility of wires. The wire gauge typically consists of a series of notches or holes with corresponding wire diameters labeled beside them. By inserting the wire into the appropriate notch or hole, the user can determine the wire's diameter. This makes the wire gauge an essential tool for measuring and selecting wires of the correct size for specific applications.
17.
The electron in the last orbit of an atom are called
Correct Answer
C. Valence electrons
Explanation
Valence electrons are the electrons located in the outermost energy level or orbit of an atom. These electrons are involved in chemical reactions and determine the atom's ability to form bonds with other atoms. Bound electrons refer to all the electrons present in an atom, including both the inner and outer electrons. Free electrons are electrons that are not bound to any particular atom and are free to move within a material. Charged electrons is not a commonly used term in the context of electron location within an atom.
18.
A 400 MCM cable has 37 strands. What is the diameter if each strand in mills?
Correct Answer
C. 104
Explanation
The correct answer is 104. This can be determined by dividing the total diameter of the cable (400 MCM) by the number of strands (37). This calculation gives us a result of approximately 10.81 MCM per strand. Since the question asks for the diameter in mills, we need to convert MCM to mills by multiplying by 1000. Therefore, each strand has a diameter of approximately 10,810 mills. Rounding this to the nearest whole number gives us 10,810 mills, which is equivalent to 104.
19.
The copper field coils of a motor was measured at 21^{o}C and found to have a resistance of 68 ohms. After the motor has run for a given time, the resistance is found to be 90 ohms. What is the hot temperature of the winding?
Correct Answer
D. None of these
20.
A secondary cell is charged with a constant current of 10 A for 10 hours. How much charge is accumulated?
Correct Answer
B. 360,000 coulombs
21.
A cell whose emf is 1.45 V has an internal resistance
of 4 ohms. What current will flow if this cell is
connected across a 1 ohms resistor?
Correct Answer
D. 0.3 A
Explanation
When a cell is connected to a resistor, a current flows through the circuit. The current can be calculated using Ohm's Law, which states that I = V/R, where I is the current, V is the voltage, and R is the resistance. In this case, the voltage of the cell is 1.45 V and the resistance of the circuit is 1 ohm. Plugging these values into the formula, we get I = 1.45 V / (4 ohms + 1 ohm) = 1.45 V / 5 ohms = 0.29 A, which is approximately 0.3 A. Therefore, the correct answer is 0.3 A.
22.
What is the diameter of a copper wire having a cross sectional area of 3,969 CM?
Correct Answer
D. None of these
23.
Which one do
When n equal resistors are connected in series to a
source of emf E volts, each having a resistance of R
ohms, which of the following statements is true? you like?
Correct Answer
D. All of these
Explanation
When n equal resistors are connected in series to a source of emf E volts, each having a resistance of R ohms, all of the given statements are true. The voltage drop across one of the resistors is equal to E/n, as the total voltage is divided equally among the resistors. The equivalent resistance of the circuit is equal to nR, as the resistors are connected in series. The current through each of the resistors is the same, as the current in a series circuit remains constant throughout. Therefore, the correct answer is "All of these".
24.
A small light bulb with a resistance of 1000 ohms is connected across a 120-V line. What is the current
through the bulb?
Correct Answer
B. 0.12 A
Explanation
The current through the bulb can be calculated using Ohm's Law, which states that current (I) is equal to voltage (V) divided by resistance (R). In this case, the voltage across the bulb is 120 V and the resistance of the bulb is 1000 ohms. Therefore, the current through the bulb is 120 V / 1000 ohms = 0.12 A.
25.
A wire whose resistance is r ohms is being cut into four equal parts. If these parts are to be connected in parallel, how much is the equivalent resistance in
ohms?
Correct Answer
D. R/4
Explanation
When the wire is cut into four equal parts and connected in parallel, the equivalent resistance can be calculated using the formula for resistors in parallel. In this case, since the wire is cut into four equal parts, each part will have a resistance of r/4 ohms. When resistors are connected in parallel, the equivalent resistance is given by the reciprocal of the sum of the reciprocals of the individual resistances. Therefore, the equivalent resistance in ohms is r/4.