eChapters

Objective
After performing this experiment you will be able to learn:
Thermal Shock Resistance in Glass.

Principle

Thermal shock occurs when different parts of an object expand at different rates due to a thermal gradient. This differential expansion creates stress or strain within the material. If this stress exceeds the material's strength, it can lead to the formation of cracks. If these cracks are not stopped from propagating, they can cause the material to fail structurally. Thermal shock is quantified by the temperature difference between the heated temperature T1 and the cold water bath temperature T2 to which the object is subsequently exposed, which can reveal any cracks or damage.

Purpose of Thermal Shock Test

Glass items often experience significant temperature changes during normal use, and the thermal shock test is designed to ensure their resistance to such conditions. For example, moving a casserole dish from a hot oven to a cool countertop might be enough to cause it to break. This test evaluates the quality, durability, and strength of glass packaging materials used for both solid and liquid food products.

Aim: To study the effect of variation of field current upon the stator current and power factor with synchronous motor running at no-load, hence to draw V and inverted V curves of the motor.

With constant mechanical load on the synchronous motor, the variation of field current changes the armature current drawn by the motor and also its operating power factor. As such, the behavior of the synchronous motor is described below under three different modes of field excitation.

Objective

After performing this experiment, you will be able to learn

Sampling methods and procedures of packaging material.

Introduction

The objective of sampling of a packaging material is to obtain a representative sample of a whole lot for the required testing and/or grading. It is expected that the test results and grading will reflect the average quality of the PM from which the sample was taken.

Principle

The sample techniques and processes outlined in this publication are grounded upon scientific principles. Since the validity of any later test result depends on the quality of the sampling and the information given with the sample, the sampler is essential to the process of selecting lots for testing and/or grading.

Every PM in the population being sampled has an equal chance of being selected, according to the random sampling principle. Usually, the sample size that is tested is very small in relation to the size of the lot that it represents. The sample must be taken carefully and in a way that gives assurance that it is genuinely representative of the lot. Similarly, in order to reduce the composite sample, all necessary.

Object: To find out the relation between transpiration and absorption. 

Material Required: Wide mouthed glass bottle, with a narrow graduated side tube, split rubber cork, water and a plant with intact root system.

Theory: The loss in weight of plant indicates the amount of water transpired. And fall in water level of the side tube indicates the amount of water absorbed. This shows that amount of water transpired is normally equal to the amount of water absorbed by the plant roots.

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Objective: To get acquainted with classmates.

Description: This is the first lab activity and has been designed to make the students feel comfortable in their new surroundings. The aim is also to help them get acquainted with their classmates as they are still new to each other. This short fun activity will help them mingle and set the tone for upcoming activities.

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Objective: To make group presentation.

Description: Group presentation refers to presentation of subject matter by few or a group of people. Group presentations are fairly common in professional life and hence, one should have a mastery over how to prepare and make group presentations. If handled properly, group presentations have several advantages over individual presentations. They are more attention grabbing and interesting as the mere presence of more than one individual introduces variety into the process. Work can be shared among the team members and knowledge and resources can be pooled for better outcome.

Object: To measure rate of transpiration of potted plant by gravimetric (Lysimeter) method. 

Material required: Potted plants, Polythene sheet, Platform and electric balance etc.

Method: Select same size and same type well watered potted intact plants. Seal the pots and the root system with a sheet of polythene so that the water loss to the atmosphere occurs only from the shoot system not from the soil (To check evaporation losses). Immediately record the weight of the potted plant and keep them in different environment such as (1) warm environment (2) cool environment (3) Calm environment.

Object: To measure the rate of transpiration by using Ganong’s potometer

Material required: Ganong’s potometer, beaker, wax or vaseline, stop watch and twig or a branch of a plant.

Theory: The amount of water absorbed is almost equal to the amount of water transpired. The difference between the two amounts is negligible. 

Method: Potometer consists of wide mouthed tube fitted with a hard cork in which a twig or branch of a plant is inserted. Other end of tube is dipped in beaker. One half of the tube is graduated. The apparatus is filled with water using the reservoir. An air bubble is inserted in the tube as shown in figure.

Objective
After performing this experiment you will be able to learn:
Gas / Vacuum packaging of foods and study their shelf life studies.

Introduction

Vacuum packaging is a food preservation technique that removes air from the package before sealing. This method involves manually or automatically placing items in a plastic film package, extracting the air, and sealing the package. The primary goal of vacuum packaging is to remove oxygen from the container to extend the shelf life of foods and, in the case of flexible packages, to reduce the volume of the contents and package. Shrink films are sometimes used to create a tight fit around the contents. Vacuum packaging is commonly used to store dry foods like cereals, nuts, cured meats, cheese, and coffee for extended periods. For short-term storage, vacuum packaging can also be used for fresh foods, such as vegetables and liquids, as it inhibits bacterial growth.

Learning outcome

The purpose is to enable the student to develop deeper knowledge understanding capabilities and attitudes in the context of group discussion.

What is the group?

A social group is a unit of two or more person in the reciprocal interaction of communication with each other.

Stages of Group Formation

Bruce Tuckman presented a model of five stages.

Orientation (Forming Stage)

During this stage, group members come together and begin to establish relationships with each other. They also clarify their goals and objectives for the group.

Power Struggle (Storming Stage)

As the group begins to work together, conflicts and differences in opinions may arise. This stage is characterized by power struggles, disagreements, and a lack of cohesion among group members.

Cooperation and Integration (Norming Stage)

In this stage, the group begins to resolve conflicts and work towards a common goal. Members begin to cooperate with each other, establish norms and rules, and develop a sense of unity.

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Objective: To practice case-based group discussion.

Overview: A case is a detailed description of anything that has happened in real life. In a case, real names are often changed to ensure confidentiality and protect the privacy, but it is not a fictitious account. A case presents a situation, or a problem and the learner is expected to suggest a solution based on the information given in the case. Case based group discussion is often used to test the analytical and reasoning ability of the participants. While participating in a case-based group discussion, the students should start by recognising and defining the problem. This is followed by listing as many solutions as possible with contributions from all the group members. In the next step, each solution is evaluated critically by the group members keeping in mind the information/ data/ facts given in the case. Finally, the best possible solution is put forth by the group. It is important to remember that there are no right or wrong solution as any option is often a trade-off.

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Objective: To practice giving an entertainment or special occasion speech.

Overview: Entertainment and/ or special occasion speeches are short, simple and often meant to be humorous and entertaining. Special occasion speeches include welcome address, award presentation/ acceptance speech, after dinner speech, farewell speech, eulogy, etc. Entertainment or special occasion speech is often an impromptu speech i.e. they are usually given without any preparation.

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Objective: To practice giving appropriate feedback.

Description: Communication is a cyclic process. The message originates from the source and is reaches the receiver. The receiver then decodes the message (i.e; makes sense)and sends a message back to the sender to convey his/her understanding or agreement with the message that has been received. Feedback not only completes the communication cycle, but also takes the process forward.

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Objective: To practice group discussion and understand the do’s and don’ts of group discussion process.

Overview: Group discussion is a form of discourse, which occurs when more than two people recognize a common problem, exchange and evaluate information and ideas. Their efforts may be directed towards a better understanding of the topic or solving a problem. Group discussion occurs in a face-to-face or co-acting situation. It is a democratic method in which equal opportunity is given to every participant to express his/ her opinion. In formal settings, group discussion takes place under the direction of leader. Group discussion is often used by academic institutions or employers to assess certain traits and skills of the participants. The number of participants usually is around eight, but there is no hard and fast rule. When being used as a method of assessment/ evaluation, the group is given a topic.

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Objective: To practice group task.

Overview: Teamwork and good interpersonal relationships are of great importance in professional life. Hence, organizations often use various methods to test qualities such as communication/influencing/leadership skills. One commonly used method is assigning group task to the candidates. Group task requires striking a balance between team goals and individual success. The team members are expected to contribute to the overall goals while furthering their individual objectives. Additionally, the evaluator can observe leadership skills, team spirit, communication skills, analytical and decision-making skills of the group members without being intrusive. One can also judge the role for which a particular member is best suited. The time assigned for a task-based group discussion/ group task can range from 10 to 60 minutes depending upon the complexity of the task.

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Objective: To practice public speaking.

Description: Public speaking refers to communication with a large number of audience in a face-to-face situation. Public speaking differs from most other types of communication as the roles of sender and receiver are distinct and different. Also, in case of public speaking, the onus of taking the interaction forward primarily lies with the speaker. Consequently, many people find it daunting and stressful and try to avoid public speaking situations.

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Objective: To prepare a non-projected audio-visual aid (chart).

Description: Audio visual aids are media that can make communication more effective through use of sound and visuals. They are of two types – projected and non-projected aids. Non projected aids are visual materials that are used as it is by the instructor and do not need any device or equipment. Examples include charts, posters, leaflets, flash cards, etc. They are easy to prepare, carry and use. They can be prepared as and when needed and multiplied at low cost.

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Objective: To prepare a non-projected audio-visual aid (folder).

Description: Folder is a single thick sheet of paper, which is usually folded once or twice. Folder contains essential information about a place, event, etc. which is printed on a good quality paper. A folder is prepared as and when needed and is distributed free of cost.

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Objective: To prepare a non-projected audio visual aid (poster).

Description: Poster is a placard displayed in a public place to raise awareness. A well-made poster must attract attention of passers-by and motivate them to take action. Here are a few tips for making effective posters:

a) A good poster should rely on pictures rather than words. While there is no strict rule regarding the number of words, try to use no more than 10- 12 words.

b) The font size should be big enough to read from a distance as posters are displayed at public places. If there is a variation in font size, increase the size as you move from top to bottom. In addition, while choosing colours, keep the background against which the poster will be displayed in mind.

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Objective: To prepare a projected audio-visual aid (power point presentation).

Description: Audio-visual aids that are magnified and projected on to a screen are called as projected audio-visual aids. There are three methods of projection:

a) Direct projection: In this case, light rays from the source of illumination pass through condenser lens, then hit the object and go through objective lens and fall on the screen. Slide projector is an example of direct projection.