Electrostatics and Electromagnetism: Basic Concepts
Electrostatic Induction
Electrostatic induction is a method used to charge a conductor without putting it into contact with an electrified object.
Coulomb’s Law
Using a torsion balance, Coulomb found that the force of attraction or repulsion between two point charges (charged bodies whose dimensions are negligible compared with the distance r that separates them) is inversely proportional to the square of the distance between them.
Electric Field Flux
The electric flux is related to the force of attraction
Read MoreAdrian Mole’s Teenage Years: A 1980s Diary
Summary
The Secret Diary of Adrian Mole, Aged 13 ¾ begins when Adrian is 13 ¾ and ends on his fifteenth birthday. During this time, Adrian experiences first love, navigates his parents’ marital problems, and pursues his ambition to become an intellectual and writer. Pandora, the love of his life, is more intelligent than Adrian, and her family is wealthier. She falls for Adrian after he rebels by wearing red socks to school instead of the required black. Together, they form a committee to continue
Read MoreAncient Greek Astronomers and Mathematicians
Apollonius
Apollonius was a great mathematician who discovered conic sections (curves obtained by cutting a cone with a plane). He also explained the retrograde motion of the planets using epicycles.
Meton
Meton discovered the Metonic cycle (19 years = 235 lunar months) to predict eclipses of the sun and moon, which recur every 19 years. The sun cycle coincides with the moon cycle every 19 years with few exceptions.
Eratosthenes
Eratosthenes discovered the Sieve of Eratosthenes to calculate prime numbers.
Read MoreUnderstanding Electricity, Magnetism, and Electromagnetism
What is Electrical Energy?
Many machines need electrical energy in order to work.
Electrical energy produces changes in matter and can be transformed into other types of energy.
It is transformed into luminous energy in a light bulb.
It is transformed into thermal energy in a vitroceramic hob.
Electrical Charges and Static Electricity
Electricity involves electric charges, which can accumulate in one place or flow from one place to another.
Electric charges can be positive or negative.
Static electricity
Read MoreFundamentals of Astronomy and Physics: Key Concepts
Fundamentals of Astronomy and Physics
4. The frequency of a wave is:
- All of the above
5. You are standing on Earth’s equator. Where is Polaris?
- On the northern horizon
6. Which of the following statements about scientific models is true?
- A model can be used to explain and predict real phenomena.
7. The energy attributed to an object by virtue of its motion:
- Kinetic energy
8. Which of the following statements is NOT true about scientific theories?
- A theory cannot be taken seriously by scientists if it contradicts
Cosmic Evolution: From the Big Bang to Dark Energy
The Future of the Universe
Cosmologists believe that the future of the universe depends on the density of its mass-energy. Two possible scenarios were initially considered: the Big Chill and the Big Crunch. However, the recent discovery of dark energy, responsible for the accelerating expansion, has introduced another possibility: the Big Rip.
- Big Chill: The Great Cooling. An open universe where matter-energy is insufficient to reach critical density, allowing gravity-free expansion.
- Big Crunch: The