Rain Sensor

A rain sensor or rain switch is a switching device activated by rainfall. There are two main applications for rain sensors. The first is a water conservation device connected to an automatic irrigation system that causes the system to shut down in the event of rainfall. The second is a device used to protect the interior of an automobile from rain and to support the automatic mode of windscreen vipers. An additional application in professional satellite communications antennas is to trigger a rain blower on the aperture of the antenna feed, to remove water droplets from the mylar cover that keeps pressurized and dry air inside the wave-guides.

Rain sensors for irrigation systems are available in both wireless and hard-wired versions, most employing hygroscopic disks that swell in the presence of rain and shrink back down again as they dry out — an electrical switch is in turn depressed or released by the hygroscopic disk stack, and the rate of drying is typically adjusted by controlling the ventilation reaching the stack. However, some electrical type sensors are also marketed that use tipping bucket or conductance type probes to measure rainfall. Wireless and wired versions both use similar mechanisms to temporarily suspend watering by the irrigation controller — specifically they are connected to the irrigation controller's sensor terminals, or are installed in series with the solenoid valve common circuit such that they prevent the opening of any valves when rain has been sensed.

Some irrigation rain sensors also contain a freeze sensor to keep the system from operating in freezing temperatures, particularly where irrigation systems are still used over the winter.

TUTORIAL LINK: https://m.youtube.com/watch?v=GnkMgYbjaao

Current Sensor

A current sensor is a device that detects electric current (AC or DC) in a wire, and generates a signal proportional to it. The generated signal could be analog voltage or current or even digital output. It can be then utilized to display the measured current in an ammeter or can be stored for further analysis in a data acquisition system or can be utilized for control purpose.

TUTORIAL LINK: https://m.youtube.com/watch?v=pN_IKGnDwIg

Carbon Catcher And Storage

Carbon capture and storage (CCS) (or carbon capture and sequestration) is the process of capturing waste carbondioxide (CO₂) from large point sources, such as fossil fuel power plant, transporting it to a storage site, and depositing it where it will not enter the atmosphere, normally an underground geological formation. The aim is to prevent the release of large quantities of CO₂ into the atmosphere (from fossil fuel use in power generation and other industries). It is a potential means of mitigating the contribution of fossil fuel emission to global warming and ocean acidification. Although CO₂ has been injected into geological formations for several decades for various purposes, including enchanced oil recovery, the long term storage of CO₂ is a relatively new concept. 

An integrated pilot-scale CCS power plant was to begin operating in September 2008 in the eastern German power plant Shwarze Pumpe run by utility Vattenfall, to test the technological feasibility and economic efficiency. CCS applied to a modern conventional power plant could reduce CO₂ emissions to the atmosphere by approximately 80–90% compared to a plant without CCS. The IPCC estimates that the economic potential of CCS could be between 10% and 55% of the total carbon mitigation effort until year 2100.

Capturing and compressing CO₂ may increase the fuel needs of a coal-fired CCS plant by 25–40%. These and other system costs are estimated to increase the cost of the energy produced by 21–91% for purpose built plants. Applying the technology to existing plants would be more expensive especially if they are far from a sequestration site. Recent industry reports suggest that with successful research, development and deployment (RD&D), sequestered coal-based electricity generation in 2025 may cost less than unsequestered coal-based electricity generation today. Storage of the CO₂ is envisaged either in deep geological formations, or in the form of mineral carbonates. Deep ocean storage is not currently considered feasible due to the associated effect of ocean acidification. Geological formations are currently considered the most promising sequestration sites. The National Energy Technology Laboratary (NETL) reported that North America has enough storage capacity for more than 900 years worth of carbon dioxide at current production rates. A general problem is that long term predictions about submarine or underground storage security are very difficult and uncertain, and there is still the risk that CO₂ might leak into the atmosphere.

TUTORIAL LINK: https://m.youtube.com/watch?v=9uVdi-3AqRE

Illusion Mirror

An illusion mirror is a pair of mirrors, one fully reflective and the other a one-way mirror, set up so that the fully reflective mirror reflects an image back into the one-way mirror, in a recursive manner, creating a series of smaller and smaller reflections that appear to recede into an infinite distance. They are used as room accents and in artwork.This effect is also seen when a subject stands between two fully reflective mirrors, as in a changing room or house of mirrors.

In a classic self-contained infinity mirror, a set of light bulbs, LEDs, or other point-source lights are placed at the periphery of a fully reflective mirror, and a second, partially reflective one-way mirror, is placed a short distance in front of it. When an observer looks into the surface of the partially reflective mirror, the lights appear to recede into infinity, creating the appearance of a tunnel of lights of great depth.

The reflections recede into the distance is that the light actually is traversing the distance it appears to be traveling. In a two-centimeter thick infinity mirror, with the light sources halfway between, light from the source only travels that one centermeter. The first reflection travels one centimeter to the rear mirror and then two centimeters to, and through the front mirror, a total of three centimeters. The second reflection travels two centimeters from front mirror to back mirror, and again two centimeters from the back mirror to, and through the front mirror, totaling four centimeters, plus the first reflection (three centimeters) making the second reflection seven centimeters away from the front mirror. Each successive reflection adds four more centimeters to the total (the third reflection appears 11 centimeters deep, fourth 15 centimeters deep, and so on).

The multiply-reflected light follows a folded path which is much deeper than the arrangement of mirrors. In theory, such a surface is infinite in area, but encloses a finite volume.

TUTORIAL LINK: https://m.youtube.com/watch?v=b2bvWArORSc

Balloon Powered Car

  Your balloon powered car demonstrates Newton's 3rd law of motion. Newton's third law states that every action has an equal and opposite reaction. When the air from the balloon goes through the straw, it carries a force. The direction of this force is in the direction of the flow of the air, in your case, to the back of the car. This is force is 'action'. According to Newton's 3rd law, there should be an equal and opposite reaction. The reaction force will then work opposite of the air flow, meaning towards front of the car. This force will cause the car to move forward. So you see, Newton's 3rd law can explain your balloon powered car. 

TUTORIAL LINK: https://m.youtube.com/watch?v=A963BG3k_h4