# Ib physics

See the guide for this topic. Temperatures describe how hot or cold an object is and determines the direction of heat flow between two bodies.

Thermal energy transfers from an object with higher temperature to another object with lower temperature. The energy transfer is called heat the flow of energy due to temperature difference. Objects which are in thermal equilibrium have the same temperature.

## IB Physics Online Revision Course

The absolute temperature of a body in the Kelvin scale is directly proportional to the average kinetic energy per molecule inside the body. Temperatures cannot be lower than absolute zero. It is the temperature where particles have zero average kinetic energy no random motion. Internal energy is the sum of total kinetic energy total thermal energy and total potential energy.

Different substances have different specific heat capacities because of different densities and physical properties. During a phase change, temperature and kinetic energy remain constant and potential energy changes which increases as molecules spread out and vice versa. Boiling: Only occurs at the boiling point a specific temperature depending on substance and occurs throughout the liquid. Evaporation: Can occur at any temperature and only occurs at the surface of the liquid.

The fastest moving particles evaporate, decreasing the average KE of the remaining particles. As a result, temperature drops. Specific latent heat of fusion: The amount of heat required to change 1kg of a substance from solid to liquid without any change in temperature. Specific latent heat of vaporization: The amount of heat required to change 1kg of a substance from liquid to gas without any change in temperature. Absolute temperature is directly proportional to the average KE and average speed of the molecules of an ideal gas.

The ideal gas is based on a list of assumptions stated previously. However, in real gases, such assumptions may not be true. Temperature and absolute temperature Temperatures describe how hot or cold an object is and determines the direction of heat flow between two bodies. Temperatures in Kelvin can be calculated by deducting the temperatures in Celsius by Absolute zero is 0K or degrees Celsius.

Internal energy Internal energy is the sum of total kinetic energy total thermal energy and total potential energy. Potential energy is associated with forces between molecules. Specific heat capacity The specific heat capacity of a substance is given by and is defined by the amount of heat needed to raise the temperature of 1kg of the substance by 1K.

Phase change Change of phase Process Kinetic energy Potential energy Solid to liquid Melting Unchanged Increases Liquid to solid Freezing Unchanged Decreases Liquid to gas Boiling Unchanged Increases Gas to liquid Condensation Unchanged Decreases During a phase change, temperature and kinetic energy remain constant and potential energy changes which increases as molecules spread out and vice versa.See the guide for this topic. However, the total energy remains constant.

Special diffraction patterns appear when light is diffracted by a single slit which is comparable to the wavelength of the light in size. We can represent this diffraction pattern by plotting the light intensity against the angle of diffraction.

The previously section shows an ideal double-slit which ignores the single-slit characteristics of each of the two single-slits. A true double-slit would exhibit closely spaced dark and light areas fringes superimposed over the single-slit pattern. The single-slit profile is said to modulate the double-slit pattern. The condition for maximum intensity is the same as that for a double-slit.

However, the angular separation of the maxima is generally much greater because the slit spacing is so small for a diffraction grating. Interference between light waves is the reason that thin films, such as soap bubbles, show colorful patterns. The interference of light waves reflects off the top surface of a film with the waves reflecting from the bottom of the surface.

When light from a point source passes through a small circular aperture, it does not produce a bright dot as an image, but rather as a diffused circular disc. The greater the diameter of the diffracting aperture such as the diameter of the pupil in the human eye or the diameter of the lens in a telescopethe better resolved clearer the image is.

Consider the diffraction pattern of two light beams diffracted by a single slit. These patterns can be categorized as resolved, just resolved, or not resolved depending on the separation between the images. The Rayleigh criterion is when two points are just resolved.

This is when the central maximum of one image coincides with the first minimum of the other. Modulation of two-slit interference pattern by one-slit diffraction effect The previously section shows an ideal double-slit which ignores the single-slit characteristics of each of the two single-slits.

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Multiple slit and diffraction grating interference patterns Multiple slit interference patterns Diffraction grating interference patterns A diffraction grating is the tool of choice for separating the colors in incident light. The equation is the condition for angles at which constructive interference occurs maximum where d is the distance between gratings and m is the order of the maximum.See the guide for this topic.

When the electrons within an atom jump from one atomic energy level to a lower energy level, energy is released in the form of light. Likewise, light is absorbed when the electrons within an atom jump from one atomic energy level to a higher energy level. The amount of energy absorbed or released can be calculated by the difference in energy eV between the two energy levels. An alpha particle is a helium nucleus. A beta particle is an electron or a positron.

Different isotopes of a given element have the same atomic number atomic number defines the type of element but different mass numbers because they have different numbers of neutrons. It is defined as one twelfth of the mass of a carbon atom. Quarks and gluons massless subatomic particles that transmit the force binding quarks together in a hadron are color-charged particles.

Similar to electrically-charged particles which interact by exchanging photons in electromagnetic interactions, color-charged particles exchange gluons in strong force interactions.

Note that color charge has nothing to do with visible colors. It is just an expression. When two quarks are close to each other, they exchange gluons and create a strong color force field that binds quarks together. The force field gets stronger as the quarks get further apart. Quarks constantly change their color charges as they exchange gluons with other quarks.

There are 3 color charges and 3 corresponding anti-color charges. Just as mixing red, blue, and green visible colors yield white, mixing red, blue, and green color charges yield color neutral. Color confinement is a phenomenon that color-charged particles cannot be isolated singularly and therefore cannot be directly observed. The color-charged quarks are said to be confined in groups hadrons with other quarks which composite to color neutral and cannot be distinguished separately. This is because the color force increases as the color-charged quarks are pulled apart. TL;DR : Color confinement or quark confinement is the phenomenon when isolated quarks and gluons cannot be observed. In addition to the three generations of leptons and quarks see previous section Quarks, leptons and their antiparticlesthere are four classes of bosons and an additional highly massive boson called the Higgs boson.

This particle was proposed in to explain the process which particles can acquire mass and was identified with the Large Hadron Collider LHC. It was built by CERN in collaboration with over scientists and engineers from over countries along with hundreds of universities and laboratories.

As an electron makes a jump from one energy level to another, energy is absorbed or released in the form of a photon. The amount of energy absorbed or released is equal to the difference between the discrete atomic energy levels and is also quantized. The energy of a photon is dependent on its frequency.Fundamental units:. Length: metre m. Mass: kilogram kg. Time: second s. Electrical current: ampere A. Temperature: kelvin K. Amount of substance: mole mol. Luminous intensity: candela cd Not required for the IB! Metric multipliers and scientific notation. Scientific notation: convenient way of expressing numbers that are too small or too big.

Important quantities! Significant figures s. Rules to count the number of significant figures:. Non-zero numbers are always significant. Errors or uncertainties in experimentation. Cause e. Errors or uncertainties in measurements. The uncertainty should always have the same number of decimal places as the value measured, and normally only 1 s. Digital instrument e. Ruler A:. Value: Errors or uncertainties in calculations.

Consider the following value: L1: 8. Now consider the following value as well: L2: 7.Matter is consisted of small structures: Molecules Thermal concepts and phase changes. Specific heat capacity c : "Energy required to increase the temperature of a units mass of a certain substance by one kelvin.

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Thermal capacity C : "Energy required to raise 1 K of an object e. Specific latent heat L : "Energy required to change the phase of a unit mass at constant temperature. During a phase change, the temperature does not change, as the kinetic energy does not increase, only the potential energy increases. Temperature of a substance changing with time, with energy being supplied by a constant power source:.

### IB Physics

The method of mixtures. Protons, neutrons and electrons all taken into account. One mole of a mono-atomic substance has a mass in grams equal to the atomic mass in u.

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Kinetic model of an ideal gas. Molecules are point particles with negligible volume. Molecules obey the laws of mechanics. No forces between molecules, except in collisions - Only kinetic energy, no potential!

Duration of a collision negligible compared to time between the collisions. The collisions between particles and from particles on walls are always elastic. Molecules have a range of speeds and move randomly. Gas laws. The Boltzmann equation. The total random kinetic energy of all particles, i. The collisions between particles and from particles on walls are always elastic Molecules have a range of speeds and move randomly.Both useful in the choice of a fuel, but other factors must be taken into account, such as transportation, availability, safeness etc.

Energy classifications.

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Primary energy: Found in nature, which has not yet been transformed or converted. Transformation process: From primary energy form into secondary energy form. Energy sources. Initial chemical potential energy decomposition of dead animals and plants. Kinetic energy of moving steam. Kinetic energy of turbines. Electrical energy generator. Fission reaction. Uranium enrichment: U absorbs neutrons. Hence, uranium needs to be enriched, i.

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Wind power. Sankey diagram. Use: represents energy and power flow, from left to right. There are three types of thermal energy transfer: conductionconvection and radiation. While conduction and convection will only occur if there is a difference in temperature, radiation will always occur. Temperature will be constant if radiant heat from surroundings equals heat lost by radiation. Movement direction: Mass of fluid is bottom heated, what decreases density, causing mass to go up, while mass that goes down is heated, leading to the formation of a convection current.

Thermal radiation. Intensity I definition: "The power received per unit area from a radiating source". The power received per unit area on the Earth may be further reduced if we take the effect of the albedo into account. Greenhouse effect.

Water vapor H2O : irrigation. Carbon dioxide CO2 : burning fossil fuels in power plants and cars. Methane CH4 : flooded rice fields, farm animals, processing of coal. Energy classifications Primary energy: Found in nature, which has not yet been transformed or converted. Fission reaction Uranium enrichment: U absorbs neutrons. Sankey diagram Use: represents energy and power flow, from left to right. Topic 8: Energy Production.See the guide for this topic. Incident electromagnetic waves with lower frequency have a smaller chance of inducing the photoelectric effect. The number of photons per unit time in the incident light is proportional to the light intensity.

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An increase in the intensity of the incident light allows a higher number of photon-electron interactions.

Therefore, more electrons are ejected. There exists a minimum energy below which electrons would not be ejected from the metal. All matters have their antimatter counterparts which resemble their corresponding matter in every way except for the sign of their charge and the direction of their spin.

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When a high energy photon collides with a nucleus, it makes a pair of electron and positron electron antimatter and gives kinetic energy to each particle. When matter collides with its corresponding antimatter, they annihilate one another with the conservation of energy, momentum, and charge.

By quantum physics, all particles do not have a defined position until they are observed. The alpha particles passed through the gold foil in most cases, a small percentage of alpha particles were deflected by small angles of deflection, and an even smaller percentage of alpha particles were deflected by large angles of deflection.

Rutherford thus deduced that the atom consists of a small compact positive nucleus where alpha particles deflect by large angles with a majority of volume existing as empty space where alpha particles pass right through.

Apart from half-lives see topic 7the activity of radioactive decay can also be shown exponentially by the law of radioactive decay. Quantum refers to the smallest discrete amount of something. A photon is a quantum of electromagnetic radiation light.

Photons exhibit wave properties under refraction or interference. Photons exhibit wave properties under its emission or absorption.

The photoelectric effect Photoelectric effect refers to the emission of electrons from a metal surface as a result of the absorption of electromagnetic wave energy. Why does the intensity of light affect the number of ejected electrons? Why is there a minimum frequency below which no electrons are ejected?

How does the frequency of the incident light affect the maximum kinetic energy of the ejected electrons? The work function corresponds to the potential energy which binds the electron to the nucleus. Pair production and pair annihilation All matters have their antimatter counterparts which resemble their corresponding matter in every way except for the sign of their charge and the direction of their spin.