WAVES
DAMPING
·
Damping is the effect that causes energy and amplitude of a wave
to be decreasing with time.
SOUND WAVES
·
Sound is a mechanical wave that propagates through matter as a
longitudinal wave. The normal hearing range is 20 Hz to 20 000 Hz. Sound which
is above the hearing range is known as ultrasound and that below the hearing
range is known as infrasound.
ELECTROMAGNETIC WAVES
1.
Electromagnetic waves are waves which consists of an electric
charge and a magnetic field oscillating at right angles to each other.
DIFFRACTION
1.
After diffraction, the wavelength, speed and frequency remain
the same. The direction of the diffracted waves depends on the size of the
aperture or obstacle.
ELECTRICITY
MOVEMENT OF CURRENTS AND ELECTRONS
·
Current always travels from the positive terminal to the
negative terminal of the battery. However, electrons always travels from the
negative terminal to the positive terminal of the battery.
POWER RATINGS
·
Electrical appliances which depend on the heating effect of
current have higher power.
SUPERCONDUCTORS
·
Superconductors will occur when the resistance of certain metals
become zero at very low temperature that nearly absolute zero.
OHM’S LAW
·
Ohm’s law states the electric current, I moving a through a
conductor is directly proportional to the potential difference or voltage
across the ends of the conductor, if the temperature and other physical factors
remains constant.
ELECTROMAGNETISM
STRENGTH OF THE MAGNETIC FIELD
·
The strength of the magnetic field due to a straight
current-carrying wire is
a.
directly proportional to the magnitude of current
b.
inversely proportional to the distance from the wire.
SOFT IRON CORE
·
The soft iron core is used frequently in electromagnets for two
reasons:
a.
It produces a stronger magnetic field by concentrating the
magnetic field lines.
b.
It can be magnetized and demagnetized easily thus reducing loss
of energy.
ELECTROMAGENTIC INDUCTION
·
Electromagnetic induction is known as the production of an
electric current by the changing of magnetic field.
LENZ'S LAW
·
Lenz's law states that the direction of the induced current is
such that the change producing it will be opposed.
ELECTRONICS
DOPING
·
Doping is adding a small number of trivalent or pentavalent
atoms into pure semiconductors to increase its conductivity. Doping produce
p-type and n-type semiconductors.
THERMIONIC EMISSION
·
The rate of thermionic emission increases if
a.
the surface area of the metal increases
b.
the temperature of the metal increases
c.
different type of metals are used
d.
the metals are coated with barium oxide or strontium oxide.
RECTIFICATION
·
Rectification is a process to convert an alternating current
into a direct current by using diode.
TRANSISTOR AS AN AMPLIFIER
·
A transistor can be used to amplify current. This is because a
small change in base current causes a large change in collector current.
RADIOACTIVITY
RADIOACTIVITY
·
Radioactivity is the spontaneous and random emission of
radioactive rays from unstable radioactive materials after which they become
more stable.
NUCLEAR ENERGY
·
Nuclear fission is the splitting of a nucleus with big mass into
two or more smaller nuclides with the release of energy.
·
Nuclear fusion is the combination of small atoms into a larger
atom and with the release of heat.
RADIOACTIVE DECAY
·
Radioactive decay is a process where an unstable nucleus becomes
a more stable nucleus by emitting radiations.
MASS DEFECT
·
In radioactive decay, one element changes into another in a
process called transmission. The mass of daughter particles is less than that
of the parent particle. This difference in mass is called the mass defect or
mass loss.
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