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AS Level Physics

Pressure at surface of liquid

+Pressure due to depth below the surface of the liquid.

A Bright Idea: AS Level Physics: Motion

Pressure at surface of liquid
+Pressure due to depth below the surface of the liquid.

A Bright Idea: AS Level Physics: Electricity

How many amps a source of current can supply in 1 hour before the source goes flat.

AS Level Physics

Amplitude is always the maximum displacement of a wave from its undisturbed position, of any wave. It therefore does not matter from which point of the wave you measure amplitude. However, how amplitude changes for stationary waves, vs. that of progressive waves, is different.


The amplitude of stationary waves is always the same, unless mode of vibration n. or length of medium L. changes.


The amplitude of progressive waves changes depending on the energy exerted on it.

A Level Physics: AS Level Physics

1) Amplitude.

Amplitude is always the maximum displacement of a wave from its undisturbed position, of any wave. It therefore does not matter from which point of the wave you measure amplitude. However, how amplitude changes for stationary waves, vs. that of progressive waves, is different.


The amplitude of stationary waves is always the same, unless mode of vibration n. or length of medium L. changes


The amplitude of progressive waves changes depending on the energy exerted on it.

2) Nodes

NB! Progressive waves don’t have nodes. So, any point on the wave will move from minimum (resting position) to one of the maxima (crest or trough) to minimum (resting position) to the other maximum (crest or trough) within a single oscillation of the wave.

A Bright Idea: AS Level Physics: Motion

The principle that:

Buoyancy force on an object submerged in a fluid
= Volume of fluid displaced (not weight of fluid displaced).

Tip: You can visually observe the change in volume, so it is easier to measure than weight. Besides, different liquids have different weights for a given amount of water displaced. So, what about other variables like density or gravitational field strength?

AS Level Physics

U = 1.66 X (10 to the power of -27) kilograms.

Relative mass of an electron: u DIVIDED BY 2000

AS Level Physics

51% (natural source): Radon and its daughter products are released into the air following the radioactive decay of uranium isotopes found in granite.
14% (natural source): Gamma rays from rocks and soil (eg. granite).
12% (natural source): Internal sources from food, water and air. The following may or may not be part of the 12%, but our bodies are also naturally radioactive.
12% (artificial source): Medicine (eg. X-rays).
10% (natural source): Cosmic rays from outer space.
1% (artificial source): Leaks from nuclear power stations and fallout from nuclear explosions.

When calculating the count rate from a radioactive source, subtract the background radiation from the reading to get the reading due to the radioactive source only.

AS Level Physics: Particles

1) Positive B particle (positron, antielectron):

The nucleus does the ff in an attempt to become more stable:
Proton decays to become a neutron, positive electron and neutrino.
Derivation: Proton loses its positive charge (a positron) to become a neutron.
Nucleus releases positron, neutrino and energy.
Mass of parent nuclide - Mass of daughter nuclide (always positive)
= Kinetic energy of recoiling daughter nuclide + Kinetic energy of B particle + Kinetic energy of neutrino.
BECAUSE
Mass-energy is conserved.
Same amount of energy is released with each B decay of a given parent nuclide.
Kinetic energy of B particle + Kinetic energy of neutrino = k (may be distributed differently but the sum is always the same).

Why positrons are so difficult to detect:

Positrons (antimatter) quickly encounter electrons (matter). The antimatter and matter annihilate each other with the release of gamma radiation.

2) Negative B particle (electron):

The nuclide does the ff in an attempt to become more stable:
Neutron decays to become a proton, negative electron and antineutrino.
Nucleus releases negative electron, antineutrino and energy.
Derivation:
Neutron loses its negative charge (electron) to become a proton.
Nucleon number remains the same, but proton number increases by 1.
Conservation of quantities is the same, except that an antineutrino is released instead of a neutrino.

3) Physical properties of beta radiation:
During beta radiation, in a single hadron (from the baryon family), a neutron (negative beta radiation) or a proton (positive beta radiation), the up quarks morph into down quarks, and vice versa, called a weak interaction.
Tip: Weakness is when you swop your identity for someone else's, but strength is to stick with those who would otherwise repel you because of one thing you have in common: your charge.

Speed: In excess of 99% speed of light.
Charge: 50% charge of alpha particle (positive or negative).
Mass (inertia): Way lower than alpha particles.
Deflection in an electric or magnetic field: Deflects way more than alpha particles travelling at a given speed (less inertia).

Penetrating power: +-1m in air, cards and sheets of aluminium up to a few millimetres thick.
Energy: Variable.

A Bright Idea: AS Level Physics: Practical

How it works:
An measuring instrument with a calibrated time-base so that measures from the screen can be used to give the values of time intervals. Can be used to measure the frequency of a periodic signal, for example the sine-wave output of a signal generator, or a sound wave from a microscope.

How to use:
Connect the Y-input to the signal (could be a direct signal like a sine wave generator, microphone for detecting sound waves, or camera for detecting light waves), and adjust the time-base controls (x.) and the Y amplifier until you see 1-5 complete cycles on the screen.
Measure to obtain an average value of L. (length).
T = L.x.
F = 1÷T

Uncertainty:
Depends on how well you can estimate L. Remembering that the trace has a finite width, you can probably measure L to an uncertainty of about 2m.m.

Checking calibration:
Check against a calibrated signal generator (that could be wrong).
Connect a microphone to the y input, sound a tuning fork of known frequency near the mic, find T by Lx and find F by 1÷T.

How to check the frequency of sound using a calibrated cathode ray oscilloscope:
Connect a mic to the y-plates of the c.r.o.

AS Level Physics

The point at which the whole weight of the object may be considered to act.
Observed when:
An object balances on a small point, where the contact force is equal to the object's entire weight acting on that point.

AS Level Physics

A physical property of matter which causes objects to experience a force when it is placed in an electric field.

AS Level Physics

Motion about a pivot.

Philosophical note: An arbitrary grounding point does not allow for growth in understanding.

AS Level Physics

Amount of charge flowing through the circuit at 1 amp in 1 second

AS Level Physics

One side of the object experiences tension, and the other side experiences compression.

A Bright Idea: AS Level Physics: Motion

Sum of the forces in any direction must be 0.
Sum of the clockwise and anticlockwise moments of the forces about any point must be 0.

AS Level Physics

Amount of charge flowing through the circuit at 1 amp in 1 second

AS Level Physics

Mass of proton = 1 unit.
Mass of neutron = 1 unit.
THEREFORE Mass of nucleon = 1 unit.

1 unit = 1.66 X (10 to the power of -27) kilograms.

Relative mass of an electron: Unit DIVIDED BY 2000.