Definitions

Radian

The angle subtended at the center of a circle of arc length equal to the radius of the circle

Circular motion?

h

Simple harmonic motion

A periodic motion caused by a linear rotating force and thus acceleration proportional to, but in the opposite direction to the displacement

Damping

Gradual loss in energy of an oscillating system

Light damping: Resistive force enough to allow multiple oscillations

Critical damping: Resistive force is just enough to allow that a damped system returns to equilibrium without oscillation

Over-damping/Hard damping: Resistive force is so high it results in a slower return to the equilibrium position (Time taken to return > Period)

Forced oscillation

Forced oscillation occurs when a periodic force is applied to an oscillating system

Resonance

If the applied periodic force has a frequency equal to the natural frequency ($f_0$) Resonance results in a significant increase in the amplitude of oscillation

Thermal equilibrium

When two objects in contact with each other are at the same temperature, there will be no net transfer of thermal energy between them

Celcius scale

Based on the thermal properties of water. It takes two fixed points; the melting point of pure ice and the boiling point of pure water and divides the range between into 100 equal increments

Thermodynamic or Kelvin scale

An absolute scale that does not depend on the physical properties of a particular substance, instead, it uses the Average kinetic energy of particles

Thermistor

Semiconductor whose resistance decreases with increasing temperature

Range: $-80\degree C \rarr 300\degree C$

Thermocouple

Use a potential difference between two different metals to produce a temperate reading

Range: $-200\degree C \rarr 1800\degree C$

Resistive Wire

Measure resistance of the wire to determine temperature.

Range: $-260\degree C \rarr 850\degree C$

1 Mole

Amount of substance containing the same number of particles as there is in 12g of Carbon-12 A mole of any substance contains a standard number of molecules given by Avogadro's Constant ($N_a$); $N_a = 6.02 * 10^23$

Ideal gas

RAVED

• R: Random movement of particles in a gas
• A: No intermonecular attraction
• V: Volume of particles is neglectable compared to the total volume occupied by the gas
• E: Collisions between molecules are elastic; no kinetic energy is lost
• D: Duration of collisions is nill, collisions are instantanoues

Boyle's Law

The pressure exerted by a fixed mass of gas is inversely proportional to its volume, provided the temperature of the gas remains constant

Charles' Law

Temperature (Kelvin) is proportional to the volume of the gas

Kinetic model of gasses

The kinetic model is a theory that links the microscopic particles to their macroscopic properties as a gas

First law of thermodynamics

Total internal energy is equal to the sum of total heat energy and total work done

Adiabatic

No thermal energy can leave or enter the system

Isothermal

Temperature remains constant

Internal energy of a system

The sum of the random distributions of kinetic and potential energies of molecules in a system

Specific heat capacity

quantity of thermal energy required to raise the temperature of a unit mass of the substance by 1 Kelvin

Specific latent heat

Thermal energy required per unit mass of a substance to change its state at a constant temperature Fusion = change to a lower energy state Vaporisation = change to a higher energy state

Sensing device

An electronic component with a property that changes when physical quantity such as light intensity changes

Light-dependant resistor

An LDR is made of high resistance semi-conducting metal

Piezo-electric transducer

Some crystals such as quartz produce a force when a potential difference is applied across them, causing their shape to change. This is known as the piezo-electric effect.

Specific acoustic impedance

Product of the density of a medium and the velocity of sound waves traveling through that medium

Attenuation

Progressive reduction of power/energy of a wave with distance as it travels along a transmission path through a medium

Ideal Op-amp

• Infinite input impedance: No current in and out through inputs
• Zero output impedance: Entire $V_\text{out}$ is distributed across load
• Infinite open-loop gain: Output is immediately saturated
• Infinite bandwidth: All frequencies across inputs are amplified evenly
• Infinite slew rate: Any change in input results in an instant change across inputs (aka No latency, but do not write this)

Feedback loops

• Increases bandwidth
• Descrease distortion
• Greater operational stability
• Reduce effective gain (...to avoid saturation)

Negative Feedback

When some of the output is fed back into the inverting input of an op-amp to minimize saturation

Carrier wave

A Carrier wave is a high-frequency Electromagnetic wave modulated in either frequency or amplitude to transfer a signal

Amplitude Modulation

In amplitude modulation (AM) the frequency of the modulated wave is constant, and the amplitude of the modulated wave varies proportionally to and in phase with the signal

Frequency Modulation

In frequency modulation (FM), the amplitude of the carrier wave remains constant. The frequency of the carrier wave is made to vary in sync with the displacement of this information signal

Bandwidth (Communication)

The range of frequencies occupied by the amplitude-modulated wave

Noise

Random unwanted signal that is added onto and distorts the transmitted signal

Analog signal

Signal has the same variation as the data and is continuously variable

Digital signal

Signal with only high and low states with no intermediate values - discrete. Due to this, repeaters can regenerate a signal matching the original one without the noise.

ADC - Analog to digital converter

Samples an input analog signal at the sampling rate and outputs the voltage of the analog signal at that time

Sampling

Take analog signal and "sample" its voltage at regular intervals called the sampling rate

Wire pairs

Potential difference between the two wires carries the signal

Wire pairs

Potential difference between the two wires is the signal

Coaxial cable

Copper core with insulation and copper sheath/braid around outside shields core from noise.

Signal to noise ratio

A signal must be distinguishable from noise, this can be measured using the signal to noise ratio. Repeaters amplify both the signal and noise, so do not affect SNR Signal regenerators completely regenerate the original signal, so that noise is removed.

Geostationary satellite

The satellite orbits in a fixed position on top of earth above the equator and orbits from west-to-east with a period of 24 hours

Newton's law of gravitation

Force between two point masses is proportional to the product of their masses and inversely proportional to the square of their separation.

Gravitational field strength

The gravitational force exerted at a point per unit mass on a small test mass at that point

Gravitational potential energy

The work done in bringing a small test mass from infinity to that point

Gravitational potential

The work done per unit mass in bringing a small test mass from infinity to that point

Escape velocity

The velocity at which an object on the surface of a body/mass must be propelled to not return to the body under their mutual gravitational attraction

Kepler's 3rd law

For planets or satellites describing orbits around the same central body, the square of the period is proportional to the cube of the radius of the orbit

Magnetic fields in a current conducting wire

Any current conducting wire will have an induced radial magnetic field around it in the direction found via The Right-hand grip rule

Weightlessness

When an object has no contact/support force acting on it

Magnetic field

Region of space where a magnetic pole experiences a force

Electric field strength

Force per unit charge

Electric potential

The work done per unit mass in bringing a small test charge from infinity to that point

Potential gradient

Rate of change of potential with respect to distance

Coulomb's law

Any two point charges exert an electric force that is proportional to the product of their charges and inversely proportional to the square of their separation

Capacitance

Ratio of charge to the potential difference

Magnetic fields in the solenoid

Solenoid rule: Thumb = Magnetic North pole, Fingers = direction of current traveling around the solenoid

Magnetic flux density

Force per unit length experienced by a long straight conductor carrying unit that is placed at right angles at that point

1 Tesla

One tesla is the uniform magnitude flux density when a wire carrying a current 1.0A is placed at right angles to a magnetic field and experiences a force per unit length of $1.0Nm^-1$

Hall effect

When a thin semiconducting wafer is placed inside a magnetic field with a small current passing through it, the charge carriers moving within the wafer are deflected (Fleming's left-hand rule) to create a potential difference (and also an electric field) across the width of the water. This is called the Hall Voltage