How to determine the right power bank for you

Power Banks  are used to provide electrical power to your phones, laptops, camcorders and handheld electrical devices. They are hand held batteries you can use to charge and power your devices when traveling, off grid areas or places with epileptic power supply.

Choosing a suitable power bank

Power Banks come in various shapes and sizes. Now a very simple rule: The bigger and denser a power bank is, the more capacity it probably has. Battery capacity means how long it can power your device or how many times it can charge your device from zero to 100%. The battery capacity should be boldly written on the packaging of any power bank you intend to buy.

When shopping for a power bank, take a good look at its capacity. It is usually expressed as something mAh. For instance, power Banks can come in capacities of 5000mAh, 10000mAh, 20000mAh and so on.

Also the power rating and battery capacity of the devices you will use the power bank with, matters.

For example, let’s say someone bought you a power bank with a capacity of 10000mAh. And you will be using it to charge a Samsung note 8 phone with a battery capacity of 3300mAh. Theoretically, the power bank should be able to charge the phone from 0-100%, 10000/3300 times or 3.03 times. However because it will be around 85% efficient when new, it should charge the phone atleast 2.5times.

Buying an original power bank

When buying an original power bank, look for the originality, look at the brand name, the packaging, engravement of the brand name and logo on the body of the power bank.

The buying of fake and substandard materials cannot be overemphasized. Most power Banks are made with lithium technology. These lithium batteries are usually purchased brand new in standard sizes from merchants and then used to build power Banks of various capacities. 

Some power bank makers can cut corners by buying and using used lithium batteries to build power Banks for sale.

How long your power bank can last

How long your power bank will last depends on the number of charge and discharge cycles it can afford before it becomes unusable. It depends on the type and quality of the lithium batteries.

Power banks made with lithium polymer batteries should at least have a charge-discharge cycle of around 200 times,

Those made of lithium ion at least 300times and those made of lithium phosphate batteries about 1000 times or more. This means a good power bank can last you for more than a year if properly used. Some power Banks can last for 2 to even 4 years.

Care for your power bank

Most power Banks will not last if misused.

When you purchase a new power bank you may be told by the manufacturers to charge it for a certain number of hours before use. Heed this counsel for your batteries to last longer.

Don’t let it drop or fall on the floor, some internal components may become broken or detached which may render it unusable.

Always use the original charger that came with the power bank to charge it.

Don’t let water or other liquids find their way into your power bank.

Don’t put your power bank in a hot room or under direct sunlight.

Don’t charge your power bank or use your power bank to power/charge a device in a hot room.

Do not over discharge your power bank, thankfully most power Banks come with a screen display to monitor the amount of battery power remaining. They are also equipped with circuit boards that prevent over charging and over discharging.

Force of Friction: Paper Power

overlapping 2 notebook pages

This simple experiment will show the power of frictional force when several sheets of paper are overlapped.

Materials needed.

2 notes or exercise books with approximately the same number of pages.

Procedure

On a table or flat surface, open the 2 books to their last pages and overlap their back covers.

Then take the next pages and overlap each one. Continue doing this until you reach their front covers.

Tell a friend to hold the binding of one book, and you hold the other one.

Try to pull the notebooks apart this way and see what happens.

The books should be very difficult to pull apart.

Explanation 

The surface of paper appears smooth to the naked eye. But when viewed under a microscope it has a rough surface. When 2 or more paper surfaces come in contact, the surfaces interlock due to frictional forces. The frictional forces existing between the paper surfaces makes it difficult to pull the notebooks apart.

Vegetable Salad: Tomato, Mozzarella and Basil Salad

Tomato, Mozzarella, Basil leaf salad

How to make Tomato, Mozzarella and Basil Salad. The salad is very simple to prepare.

Ingredients.

4 ripe tomatoes

Salt

Pepper

8 Basil leaves

One large Mozzarella 

Procedure.

Cut the tomatoes into small slices of about ¼ inches thick. Put inside a bowl, drain the tomato liquid then sprinkle lightly with salt.

Cut the mozzarella into 8 slices

Next layer the tomato slices, Basil leaves and mozzarella slices on a flat plate. Sprinkle salt and pepper. Drizzle with oil and serve.

Methods of Soil Exploration

Machine operated soil drill

Borings are the main procedure used for soil exploration on site. There are different types of borings. They can generally be grouped into 3 types, they are:

  • Trial pits of up to 3m deep
  • Borings of up to 30m deep
  • Headings and Shafts

Trial pits

Trial pits are pits of about 1.2m by 1.2 m. They can be dug with the use of labour or excavating machines. Trial pits should be dug  at distances of 20m apart and clear of the positions of the building’s foundation. Trial pits are economical up to a depth of 3m. Trial pits are suitable for small-scale works. The main advantage of this method is that soil and rock samples can easily be exposed and examined.

Deep boring.

This is the process by which hand or mechanical/machine boring tools are used to drill holes into the soil for investigative purposes. Deep borings are suitable for medium to  large scale works such as high rise buildings.

Hand or mechanical auger borings are cheap methods of boring soils which can stand unsupported. Holes can be sunk up to 3m. For soils that cannot stand on their own such as loose soils, steel casing can be dug surrounding the bored area.

Boring rig

A steel casing called shell is used to collect soil samples for testing.

Auger sampling shell

It is done at regular intervals as hole is being dug.

For deeper borings of up to 30m, machine operated drilling must be employed. They are of many types. There is the percussion boring in which the soil formation is broken up by repeated blows after which water is added to the hole as the work proceeds. The water helps to wash out the soil debris by pressure washing or by shell auger. The samples collected by this method are disturbed samples because of the repeated blows to the soil formation.

Wash boring method uses only a strong jet of water or drilling mud to bore deep holes in the soil. This method produces undisturbed samples. However, it is suitable if the soil does not contain boulders or large gravels.

Rotary drilling is a method used for boring of soil with rock formations. The drilling bit is fitted with industrial diamond to break the rock formations. Drilling mud, water or compressed air is jetted into the drilled hole to flush out the rock debris.

Headings and Shafts.

Headings and Shafts are employed to explore steeply dipping strata. It is best suited for very large scale works such as dams, power stations etc. The method is used to create exploration tunnels. The advantage they have over pits drills is that they can be easily drained of water and also easy removal of soil debris. Shafts are bored using large power driven augers. The sides of the shafts must be supported to protect the work personnel engaged in soil inspection.

Choice of soil exploration methods.

The choice of different exploration methods will depend on the following factors:

  • Topography.
  • Nature of ground.
  • Cost.

Method of Soil Investigation on Building Site

boring hole for soil investigation on site

The construction of buildings, dams, reservoirs, docks and other types of construction works, soil investigation will require deep and closely spaced borings.

Borings will reveal the types of soil layers beneath the proposed foundation, and whether or not it will be suitable to carry the proposed structure safely.

Borings should be dug in a regular pattern in such a way that it gives a clear picture of all significant variations of the soil within the site.

Investigative boreholes should be at least 1.5m deep. Three main factors will govern the depth of exploration:

Depth to which the foundation load will act on beneath the base of the foundation.

Depth to which weathering will affect the soil.

Depth at which impervious strata occur.

Some investigative borings  can be up to 6m deep.

The standard depth for building structures is up to 1.5 times the breadth of the foundation.

How soil is stressed under foundation loading

Load of the structure is transferred to the foundation and then to the surrounding soil beneath the foundation. The soil stress beneath the foundation is reduced with depth.

Bulb pressure distribution under pad foundation

The diagram above shows the soil stresses below a pad foundation. Notice that at 1.5b below the foundation level, the bulb stress is 0.2 of the original stress just under the foundation. This value is higher for a strip foundation as shown below.

Bulb pressure distribution below a strip foundation.

The reason for this is because strip foundation is continuous while pad foundation is isolated.

Manchester City Win Premier League Title

Manchester City lift Premier League Throphy

Manchester City have won the English Premier League Title on the final day of the 2021/2022 season.

Mamchester City Players Celebrating goal Scored

They came from 2 goals down to beat Aston Villa by 3-2. Manchester City finished top of the table with 93 points.

Liverpool beat Wolves 3-1 to finish in second place with 92 points. No quadruple for them this season.

Chelsea came third with a distant 74 points while Tottenham finished 4th with 71 points.

Burnley, Watford and Norwich finished 18th(35 points), 19th (23 points) and 20th(22 points).

Manchester City, Liverpool, Chelsea and Tottenham qualify for the Champions League.

Arsenal and Manchester United qualify for Europa League.

WestHam qualify for  Conference League .

Burnley, Watford and Norwich are relegated.

English Premier League (Club Stats)

Manchester City scored the highest goals of the season: 99 goals followed by Liverpool with 94 goals, Chelsea came third with 76 goals scored.

Best defence goes to Manchester City, Liverpool coming second and Chelsea, coming a distant third. City and Liverpool both conceded 26 goals this season and Chelsea conceded 33 goals.

Norwich City is the team with the worst defence shipping a total of 84 goals conceded.

English Premier League (Player Stats.)

Heung Min Son of Tottenham is the highest goal scorer this season with 23 goals, followed by Salah of Liverpool with 22 goals and third is Christiano Ronaldo with 18 goals.

 Salah top the assist chart with 13 assists, followed by Alexander with 12 assists, both of Liverpool. Barnes of Leicester City is third with 11 assists.

Final Standings: English Premier League

English Premier League Table: Final Standings . Source: BBC sports.