Science Q&A: Electronics, Energy, Health & Environment
How Pure Semiconductors Become N-Type
An n-type semiconductor is created when pure semiconductors, like Si and Ge, are doped with pentavalent elements. When a pentavalent atom takes the place of a Si atom, four of its electrons bond with four neighboring Si atoms.
Difference Between P-Type and N-Type Materials
N-type semiconductors have an excess of electrons, while p-type semiconductors have an excess of “holes” where an electron could exist.
How a Diode Works
It allows current to flow easily in one direction but severely restricts current from flowing in the opposite direction. Diodes are also known as rectifiers because they change alternating current (AC) into pulsating direct current (DC).
Uses and Applications of Diodes
The most basic function is changing AC current to DC current by removing some part of the signal. This functionality makes them rectifiers. They are used in electrical switches and in surge protectors because they can prevent a spike in voltage.
How a Radio Transmitter Works
A radio transmitter is an electronic circuit which transforms electric power from a power source, a battery or mains power, into a radio frequency alternating current to apply to the antenna, and the antenna radiates the energy from this current as radio waves.
Major Sections of a TV Receiver
It consists of 5 main stages:
- An RF tuner section that selects the desired frequency.
- A mixer that combines the received RF signal with a local oscillator signal to produce an intermediate frequency (IF) signal.
- An IF filter that eliminates unwanted frequencies and noise.
- A demodulator that retrieves the signal.
What is Satellite TV?
Satellite television is a service that delivers television programming to viewers by relaying it from a communications satellite orbiting the Earth directly to the viewer’s location. The signals are received via an outdoor parabolic antenna commonly referred to as a satellite dish and a low-noise block downconverter.
ROM vs RAM: Key Differences
RAM stands for Random Access Memory, and ROM stands for Read Only Memory. RAM is memory that stores the data that you’re currently working with, but it’s volatile, meaning that as soon as it loses power, that data disappears. ROM refers to permanent memory. It’s non-volatile, so when it loses power, the data remains.
Microprocessor: Basic Parts and Function
Components of the microprocessor are ALU, Control unit, Input-output devices, and Register array. ALU (arithmetic logic unit) performs both arithmetic and logical operations.
Uses of a Microprocessor
General-purpose microprocessors in personal computers are used for computation, text editing, multimedia display, and communication over the Internet.
Relation Between Work and Energy
Work and energy are closely related. When you do work to move an object, you change the object’s energy. You (or an object) also expend energy to do work. In fact, energy can be defined as the ability to do work. Energy can take a variety of different forms, and one form of energy can transform to another.
Kinetic vs Potential Energy
Potential energy is energy stored in an object due to its position or arrangement. Kinetic energy is energy of an object due to its movement – its motion. All types of energy can be transformed into other types of energy.
Advantages of Electrical Energy
It can be easily converted into other energy forms and can be safely and securely transported over long distances with low losses. It is a steady source of power, comes from both renewable resources and non-renewable resources. It is a clean form of energy which is free from smoke, fumes, and poisonous gases.
Why the Sun is Earth’s Ultimate Energy Source
Through photosynthesis, green plants prepare food that is eaten by animals so energy from green plants is transferred to animals by the food chain. Sun is the ultimate source of energy on earth which leads to the origin of other energy such as wind energy, hydro energy, and geothermal energy.
Examples of Renewable Energy Sources
They are natural and self-replenishing, and usually have a low- or zero-carbon footprint. Examples of renewable energy sources include wind power, solar power, bioenergy (organic matter burned as a fuel) and hydroelectric, including tidal energy.
How a Solar House Heating System Works
The collector has an airtight and insulated metal frame and a black metal plate for absorbing heat with glazing in front of it. Solar radiation heats the plate that, in turn, heats the air in the collector. An electric fan or blower pulls air from the room through the collector, and blows it back into the room.
Generating Electricity from Geothermal Energy
Geothermal power plants use steam to produce electricity. The steam comes from reservoirs of hot water found a few miles or more below the earth’s surface. The steam rotates a turbine that activates a generator, which produces electricity.
Environmental Impact of Fossil Fuels
When fossil fuels are burned, they release large amounts of carbon dioxide, a greenhouse gas, into the air. Greenhouse gases trap heat in our atmosphere, causing global warming.
Defining the Calorie Unit
Calorie information is often given in kcal, which is short for kilocalories. It may also be given in kJ, which is short for kilojoules. As a guide: an average man needs 2,500 kcal a day.
Ways to Control Pollution
- Plant grass, trees and shrubs in bare areas.
- Properly dispose of motor oil and household chemicals.
- Use fertilizers and pesticides sparingly on lawns and gardens.
- Put trash in its place.
- Organize neighborhood cleanups.
- Recycle plastic, glass, and paper.
Energy Conservation in Transport
Avoid extensive use of private vehicles. Try to use public transportation whenever possible. Remove extra weight in the car. Unwanted items like a flat tyre, unwanted luggage in the vehicle, especially heavy ones, can reduce the vehicle’s fuel efficiency.
Useful Activities of Bacteria
Most bacteria are good for us. The bacteria in our bodies help degrade the food we eat, help make nutrients available to us and neutralize toxins, to name a few examples. Also, they play an essential role in the defense against infections by protecting colonized surfaces from invading pathogens.
Cancer: Symptoms and Treatments
Symptoms can include:
- Fatigue.
- Lump or area of thickening that can be felt under the skin.
- Weight changes, including unintended loss or gain.
- Skin changes, such as yellowing, darkening or redness of the skin, sores that won’t heal, or changes to existing moles.
Protecting Yourself from Germs
Hand-washing is one of the easiest and best ways to protect yourself from germs and most infections. Wash your hands with soap and water for at least 20 seconds. Wash your hands before making or eating food, after coughing or sneezing, after changing a diaper, and after using the toilet.