All questions of Utilization of Electrical Energy for Electrical Engineering (EE) Exam

Electrodeposition is a well-known method to produce in situ metallic coatings by the action of an electric current on a conductive material immersed in a solution containing a salt of the metal to be deposited.

Decrease in duration of stops and its effect on schedule speed

Introduction:
In transportation systems, the schedule speed represents the average speed at which a vehicle is expected to travel over a given distance. The duration of stops, such as when a vehicle halts at a station or a bus stop, directly impacts the schedule speed. In this question, we are considering the effect of decreasing the duration of stops on the schedule speed.

Explanation:
When the duration of stops is decreased, it means that vehicles spend less time stationary during their journey. This reduction in stop duration has the following effects:

1. Reduced time loss:
By decreasing the duration of stops, vehicles can spend more time in motion, resulting in reduced time loss. This means that the time spent waiting at stops is minimized, allowing vehicles to cover more distance in a given time period.

2. Increased average speed:
Since vehicles spend less time stationary and more time in motion, the average speed of the vehicle increases. The average speed is calculated by dividing the distance traveled by the total time taken. With reduced stop duration, the total time taken decreases, while the distance traveled remains the same. As a result, the average speed increases.

3. Effect on schedule speed:
The schedule speed is a predetermined speed at which a vehicle is expected to travel. It is set based on factors such as traffic conditions, road design, and passenger demand. When the duration of stops is decreased, the average speed of the vehicle increases. This means that the vehicle can cover the same distance in less time, thereby completing its journey ahead of schedule.

Therefore, the decrease in the duration of stops leads to an increase in the schedule speed. The vehicle can adhere to the schedule more efficiently, potentially allowing for improved reliability and reduced travel time for passengers.

Conclusion:
When the duration of stops is decreased, the schedule speed increases. This is due to the reduction in time loss and increased average speed resulting from less time spent stationary. The increase in schedule speed can positively impact the efficiency and reliability of transportation systems, benefiting both passengers and service providers.

The length of arc required in welding depends on various factors. Let's discuss each of these factors in detail:

a) The kind of electrode used, its coating, and its diameter:
- Different types of electrodes are used for different welding processes. For example, in shielded metal arc welding (SMAW), commonly known as stick welding, electrodes with different coatings are used. The coating on the electrode helps in providing protection from the atmosphere and also influences the characteristics of the arc.
- The diameter of the electrode also affects the length of the arc. A smaller diameter electrode requires a shorter arc length, while a larger diameter electrode requires a longer arc length.

b) The magnitude of current used:
- The magnitude of current used in welding plays a crucial role in determining the length of the arc. Higher current levels generally require a longer arc length.
- The length of the arc is directly proportional to the current. As the current increases, the arc length also increases. This is because higher current levels generate more heat, and a longer arc is needed to dissipate the heat properly.

c) The position of welding:
- The position of welding, whether it is flat, horizontal, vertical, or overhead, affects the length of the arc.
- In vertical and overhead welding positions, a shorter arc length is generally preferred to prevent excessive spatter and maintain control over the molten metal.
- On the other hand, in horizontal and flat positions, a slightly longer arc length may be required to ensure proper penetration and fusion.

Considering all the factors mentioned above, the correct answer to the question is option 'D' - all of the above. The length of arc required in welding depends on the kind of electrode used, its coating, and its diameter, the magnitude of current used, as well as the position of welding. All these factors need to be taken into consideration to determine the appropriate length of the arc for a particular welding process.

Introduction:
When selecting an electric motor for a flour mill, various electrical characteristics need to be considered. These characteristics determine the motor's performance, efficiency, and suitability for the specific application. Among these characteristics, the least significant one is the braking capability of the motor.

Explanation:

1. Starting characteristics:
Starting characteristics refer to the motor's ability to start the load attached to it. It includes parameters such as starting torque, starting current, and starting time. These characteristics are crucial in ensuring that the motor can start the flour mill efficiently and reliably. If the motor lacks sufficient starting torque or takes too long to start, it may result in operational issues and delays in the flour mill's production.

2. Running characteristics:
Running characteristics encompass the motor's performance during normal operation. These include parameters such as rated power, speed, efficiency, and load-carrying capacity. The motor should be capable of delivering the required power and maintaining the desired speed under normal operating conditions. The efficiency of the motor is also important as it affects energy consumption and operational costs.

3. Efficiency:
Efficiency is a critical factor in motor selection as it directly affects the operating costs of the flour mill. A more efficient motor utilizes electrical energy more effectively, resulting in lower energy consumption and reduced electricity bills. High-efficiency motors also produce less heat, which contributes to improved reliability and longevity.

4. Braking:
Braking capability refers to the motor's ability to decelerate or stop the load when necessary. In the context of a flour mill, braking may be required to halt the mill's operation quickly or to prevent the mill from running out of control. However, the braking characteristic is the least significant in motor selection for a flour mill because:

- Flour mills typically have external braking systems specifically designed for controlling the mill's rotation and stopping it efficiently. These systems are separate from the motor and are responsible for providing the necessary braking force.
- Electric motors used in flour mills are generally not designed to provide significant braking torque. Their primary function is to provide rotational motion to the mill, and braking is secondary.
- If the motor lacks adequate braking capability, it can be compensated by using an appropriate external braking system without compromising the motor's overall performance and suitability for the flour mill application.

Conclusion:
Among the various electrical characteristics considered when selecting an electric motor for a flour mill, the least significant one is the braking capability. Starting characteristics, running characteristics, and efficiency play more crucial roles in ensuring the motor's performance, reliability, and cost-effectiveness. Although braking capability is necessary, it can be achieved through separate external braking systems specifically designed for controlling the flour mill's operation.

Understanding Tractive Effort in Trains
Tractive effort is essential for the efficient operation of trains. It is the force exerted by the train's wheels to move the train forward and is influenced by several factors. Here’s a breakdown of why tractive effort is required:
1. Accelerate the Train Mass
- Tractive effort is needed to overcome inertia when starting and to accelerate the train to the desired speed.
- The greater the mass of the train, the more tractive effort is required to achieve acceleration.
2. Overcome Train Resistance
- Trains face resistance due to friction, windage, and curve resistance.
- Friction arises between the train wheels and the track, while windage is caused by air resistance as the train moves.
- Curve resistance occurs when the train navigates turns, requiring additional force to maintain speed.
3. Overcome the Effect of Gravity
- When trains travel on inclined tracks, they must exert additional tractive effort to counteract gravitational forces.
- This is especially relevant in hilly or mountainous terrains where the gradient can significantly affect performance.
Conclusion
- Therefore, tractive effort is vital for all these functions: to accelerate the train mass, overcome resistance, and counteract gravity.
- The correct answer, "D) All of the above," reflects the comprehensive role of tractive effort in ensuring smooth and efficient train operations across varying conditions.

The illumination of various points on a horizontal surface illuminated by the same source varies as the cosine of the angle of incidence.

In electric discharge lamps, the light is produced through the process of ionization in a gas or vapor. This phenomenon occurs due to the flow of electric current through the lamp.

Explanation:
- Electric discharge lamps, such as fluorescent lamps, neon lamps, and sodium vapor lamps, work on the principle of ionization. These lamps contain a gas or vapor-filled chamber with two electrodes, known as a cathode and an anode.
- When a high voltage is applied across the electrodes, it creates an electric field within the lamp. This electric field causes the gas or vapor molecules to become excited and gain energy.
- As the energy level of the gas or vapor molecules increases, some of the electrons in the outermost orbit of the atoms get detached from their parent atoms, creating free electrons.
- These free electrons collide with other gas or vapor molecules, causing further ionization. This process continues, leading to a chain reaction of ionization and the release of more free electrons.
- As the free electrons return to their original energy levels, they emit photons of light. This light emission occurs at specific wavelengths, depending on the type of gas or vapor present in the lamp.
- Different gases or vapors emit different colors of light. For example, neon gas emits red light, while mercury vapor emits blue or ultraviolet light.
- The photons emitted by the ionized gas or vapor create visible light, which is observed as the illumination of the lamp.
- The intensity and color of the light produced by the lamp can be controlled by varying the gas or vapor composition and the voltage applied to the electrodes.

In summary, the light in electric discharge lamps is produced through the process of ionization in a gas or vapor. The flow of electric current through the lamp causes the gas or vapor molecules to become excited and release photons of light as the electrons return to their original energy levels. This phenomenon allows electric discharge lamps to produce visible light for various applications.