Scalars:
Distance, speed, time, mass, energy and temperature
Vectors:
Force, weight, velocity, acceleration, momentum, electric field strength and
gravitational field strength
Mass: Measure of quantity of matter in an object at rest relative to the observer
Weight: Gravitational force on an object that has mass
Velocity: Speed in a given direction
Circular motion:
(a) speed increases if force increases, with mass and radius constant
(b) radius decreases if force increases, with mass and speed constant
(c) an increased mass requires an increased force to keep speed and radius
constant
Moment: force x perpendicular distance from pivot
Centre Of Gravity: The point where all the weight of an object seems to act
Energy may be stored as:
Kinetic
Gravitational potential
Chemical
Elastic (strain)
Nuclear
Electrostatic
Internal (thermal)
Can be transferred by:
Forces (mechanical work done)
Electrical currents (electrical work done)
Heating
Electromagnetic, sound and other waves
Solar
Advantages:
1. Renewable
2. No pollution or greenhouse gases
Disadvantages:
1. Intermittent supply (Not always available)
2. Uses a lot of space
3. Expensive to setup
Biofuels
Advantages:
1. Renewable energy resource
2. Relatively cheaper in cost
3. Carbon neutral
Disadvantages:
1. Environmental pollution from gases produced contributes to global
warming
2. Plants take time to grow
Hydropower
Advantages:
1. Renewable energy resource
2. No pollution
Disadvantages:
1. Expensive to set up
2. Damages surrounding environment
Geothermal
Advantages:
1. Clean source of naturally available thermal energy
2. Renewable
Disadvantages:
1. Environmental pollution caused by the release of poisonous gases such as
hydrogen sulphide into the atmosphere
2. Not widely available
Fossil Fuels
Advantages:
1. Widely available at a large sale
2. Relatively cheaper cost of production
Disadvantages:
1. Environmental pollution from gases produced causes global warming
2. Non-renewable
Nuclear
Advantages:
1. Reliable
2. No pollution
Disadvantages:
1. Non-renewable
2. Risks of accidents and pollution from the improper disposal of
radioactive wastes
Transverse:
1. Electromagnetic Radiation
2. Water Waves
3. Seismic S-waves (Secondary)
Longitudinal:
1. Sound Waves
2. Seismic P-waves (Primary)
Snell’s Law: sini x n1 = sinr x n2
Refractive index in air = 1
Fixing Long-sightedness: Converging Lens
Fixing Short-sightedness: Diverging Lens
Monochromatic: Light of a single frequency
Uses:
Radio Waves: Radio and television transmissions, astronomy, radio frequency
identification (RFID)
Microwaves: Satellite television, mobile phones (cell phones), microwave ovens
Infrared: Electric grills, short range communications such as remote controllers
for televisions, intruder alarms, thermal imaging, optical fibres
Visible Light: Vision, photography, illumination
Ultraviolet: Security marking, detecting fake bank notes, sterilising water
X-Rays: Medical scanning, security scanners
Gamma Rays: Sterilising food and medical equipment, detection of cancer and
its treatment
Harmful Effects:
Microwaves: Internal heating of body cells
Infrared: Skin burns
Ultraviolet: Damage to surface cells and eyes, Leading to skin cancer and eye
conditions
X-Rays and Gamma Rays: Mutation Or Damage of Cells in body
Higher Frequency = Higher Energy
Speed of Electromagnetic Waves In Vacuum: 3.0 x 108 m/s
Benefits Of Digital Signals:
1. Increased Rate of Transmission Of Data
2. Increased range due to accurate signal regeneration
Speed Of Sound:
1. Air: 330-350 m/s
2. Liquid: 1500 m/s
3. Solid: 5000 m/s
Ultrasound: Sound with frequency greater than 20kHz
Used in non-destructive testing of materials, medical scanning of soft tissue and
sonar
Magnetic Field: A region in which a magnetic pole experiences a force
Electric Field: A region in which an electric charge experiences a force
Direction Of Magnetic Field at a point: Direction of the force on the North pole
of a magnet at that point
Electric Current (I = Q/t): The charge passing a point per unit time
E.m.f: The electrical work done by a source in moving a unit charge around a
complete circuit
Potential Difference: Work done by a unit charge passing through a component
Kilowatt-hour(kWh): Electrical energy used by a 1 kW appliance in 1 hour
Operation of an iron-cored transformer:
● Alternating current in primary coil generates changing magnetic field
● Iron core transfers magnetic field to secondary coil
● Secondary coil cuts magnetic field
● E.m.f induced in secondary coil
Scattering of alpha-particles provides evidence for:
1. A very small nucleus surrounded by mostly empty space
2. Nucleus containing most of the mass of the atom
3. Nucleus being positively charged
Nuclide Notation
A = Mass Number
Z = Atomic (Proton) Number
Sources Of Background Radiation:
1. Radon gas
2. Rocks and Building
3. Food and drink
4. Cosmic Rays
Isotopes can be reactive due to an excess of neutrons in the nucleus and/or
nucleus being too heavy
Half-life: Time taken for number of radioactive nuclei in the particular sample
to halve
Safety Precautions for ionising radiation:
1. Reducing exposure time
2. Increasing distance between source and living tissue
3. Using shielding to absorb radiation
Light Year = 9.5 x 1015 m
Diameter Of Milky Way = 100000 light-years
Hubble’s Constant = 2.2 x 10-8/s
Redshift = Increase in the observed wavelength of electromagnetic radiation
emitted from receding stars and galaxies
Cosmic Microwave Background Radiation:
Microwave radiation of a specific frequency which is observed at all points in
space around. It was produced shortly after the universe was formed and has
expanded into the microwave region of the electromagnetic spectrum as the
Universe expanded
Speed at which a galaxy is moving away from Earth can be found from change
in wavelength of the galaxy’s starlight due to redshift
Distance of a far galaxy can be determined using the brightness of a supernova
in that galaxy