Physics Flashcards
what the equation for Pressure?
P = F/A
pressure (Pa) = force (N) /area (m^2)
What is the equation for mass density?
pm = m/V
mass density (kg/m^3) = mass (kg) / volume (m^3)
What is the equation for weight density?
pw = w/V
weight density (N/m^3) = weight (N) / volume (m^3)
How is weight density obtained from mass density?
by multiplying mass density by the acceleration of gravity (9.8m/s^2)
in what unit is pressure measured in for GASES?
atmospheres (atm = 1 at sea level, 0 degrees celsius)
waves have three measurable properties which are…
wavelength, amplitude, frequency
describe the relationship between wavelength and frequency
they are inversely proportional
- longer wavelength = lower frequency
- shorter wavelength = higher frequency
Wavelength can be measured in …
Angstroms (A) or nanometers (nm)
What is reflection, refraction and absorption?
- reflection occurs when light (travelling as particles) hit a smooth or bumpy, bright surface, causing it to project back towards its origin either in a straight line or in multiple directions.
- refraction is when light (travelling as particles) hits a transparent surface, causing it to travel past the surface to the other side.
- absorption is when light is absorbed into the medium or surface
what happens to light when it travels through a surface that is a different medium to air?
the wavelength of the light will change, causing it to change in direction, known as angle of refraction.
how is colour perceived?
- by the way different objects reflect, refract or absorb light.
- different objects reflect only certain wavelengths of light and absorb the rest.
- the light that is reflected is the colour that is perceived.
- white light is a reflection of all the wavelengths.
What are the main colours of the light spectrum?
red, yellow, blue
How is colour and light detected by the eyes?
by cone cells and rod cells in the retina
electricity exists because..
all particles which make up the universe are charged (neg/pos)
an electric current is…
it is measured in…
- the movement or flow of charged particles from one place to another
- volts or amperes
electric charge is…
it is measured in…
- the positive and negative forces which make up atoms
- coloumbs
What is coloumb’s law?
a measure of the electrical force between two charged particles, which is inversely proportional to the distance between them.
What is an electric field?
a field of electrical charge surrounding a particle, which is equivalent to its net charge.
- E = Fc/q
- electric field = couloumb force / net charge or particle
What is an Ampere?
- the number of coloumbs passing a certain point per second
- I = C/s
- electric flow = coloumb/second
What is a Volt?
- the unit measuring the amount of pressure pushing an electric flow through a circuit.
What are the relationships between conduction of an electric current and diameter, length, voltage and resistance of a wire/circuit?
the conduction of a current is directly proportional to the diameter and voltage and inversely proportional to the length and resistance.
What are the three equations for Ohm’s Law?
- Voltage (V)
- Resistance (R; measured in ohm’s)
- Current (I; measured in amperes)
V = IR R = V/I I = V/R
What are the four components of an electric circuit?
- generator (battery)
- conductor (wire)
- resistor
- load (electrons)
What are the 4 components of sound waves? and how do they relate?
- wavelength (lambda)
- Frequency (f; Hz)
- Amplitude
- Speed (k)
Wavelength = k / f
