Please enable JavaScript.
Coggle requires JavaScript to display documents.
Physics GCSE - Coggle Diagram
Physics GCSE
Thermal physics
-
-
Heating changes energy stored within system by increasing energy of particles that make up a system. Either raises temp of system or produces change of state.
Changes of temperature
Amount of energy stored stored or released from a system as its temperature changes calculated with: ∆E = mc∆⩉, change in thermal energy
Mass, m, in kilograms, kg
Specific heat capacity, c, ∆⩉,in joules per kilogram per degree Celsius, *C
Specific heat capacity of a substance is amount of energy required to raise temperature of one kilogram of substance by 1 degree Celsius.
If temp of system increases, increase in temp depends on the mass of substance heated, type of material and energy input to system.
Changes Of State
Changes of state are physical changes which differ from chemical changes because material recovers its original properties if change is reversed
-
Energy for a change of state = mass x specific latent heat - E(J, joules) = m(mass, kg)L(specific latent heat, J/kg)
Thermal energy transfer
all bodies, no matter what temp, emit and absorb infrared radiation. hotter the body, more infrared radiation it radiates at a given time.
Amount of radiation emitted also depends on surface area, colour and texture. A perfect black body is an object that absorbs all radiation incident on it. A black body does not reflect or transmit any radiation. Since a good absorber is also a good emitter, a perfect black body would be best emitter.
A body at constant temperature is absorbing radiation at same rate as it is emitting radiation. Temp of a body increases when body absorbs radiation faster than it emits radiation.
Temperature of Earth depends on many factors including: rates of absorption and emission of radiation, reflection of radiation into space.
Electricity
Equations:
V=IR - voltage (V, volts) = Current (A, amps) x resistance (omega, ohms)
Q = It - Q charge flow (C, coulombs), I current (A, amps), t time (seconds, s)
E = Pt - E energy transferred (J, joules), P power (W, watts), t time (s, seconds)
E = QV - E energy transferred (J, joules), Q charge flow (C, coulombs), V potential difference (V, volts)
E = IVt - E energy transferred (J, joules), I current (A, amp), V potential difference (V, volts), t time (s, seconds)
P = IV - P power (W, watts), I current (A, amps), V voltage (V, volts)
P = I²R - P power (W, watts), I current (A, amps), R resistance (omega, ohms)
Static charge
When certain materials are rubbed against each other they become electrically charged. Negatively charged electron are rubbed off one material and onto the other. The material that gains electrons becomes negatively charged. The material that loses electrons is left with an equal positive charge.
When two electrically charged objects are brought close together they exert force on each other. Two objects that carry the same type of charge repel. Two objects that carry different types of charges attract.
Electric Fields
A charged object creates an electric field around itself. The electric field is strongest close to the charged object. The further away from the charged object, the weaker the field.
A second charged object placed in the field experiences a force. The force gets stronger as the distance between the objects decreases.
-
-
-
Matter Physics
Density
-
Solid most dense, liquid second, gas least dense
-
-
-
Pressure
-
-
p(pressure, pascals, Pa) = h(height, m) x p(density, kg/m3) x g(gravitational field strength, N/kg, just x 10) - p =hpg
Buoyancy
a partially submerged object experiences a greater pressure on the bottom surface than on the top surface. This creates a resultant force upwards. this force is called the upthrust.
Atmospheric pressure
the atmosphere is a thin layer of air round the Earth. The atmosphere gets less dense with increasing altitude
Air molecules colliding with surface create atmospheric pressure. Number of air molecules above surface decrease as height of surface above ground level increases. So as height increases there is always less air above above a surface than at a lower height. Atmospheric pressure decreases with increase in height.
-
Electromagnetism
Poles of a magnet
-
-
-
-
-
An induced magnet is a material that becomes a magnet when it is placed in a magnetic field. Induced magnetism always causes a force of attraction.
-
Magnetism
The region around a magnet where a force acts on another magnet or on a magnetic material (iron, steel, cobalt and nickel) is called the magnetic field.
-
The strength of the magnetic field depends on the distance from the magnet. The field is strongest at the poles of the magnet
The direction of the magnetic field at any point is given by the direction of the force that would act on another north pole placed at that point
The direction of a magnetic field line is from the north (seeking) pole of a magnet to the south(seeking) pole of the magnet.
A magnetic compass contains a small bar magnet. The Earth has a magnetic field. The compass needle points in the direction of the Earth's magnetic field.
Electromagnets
-
The strength of the magnetic field depends on the current through the wire and the distance from the wire
Shaping a wire to form a solenoid increases the strength of the magnetic field created by a current through the wire
-
The magnetic field around a solenoid has a similar shape to that of a bar magnet. Adding an iron core increases the strength of the magnetic field of a solenoid
-