Sources of mains electricity Mains electricity comes from a power station and its current is the alternating current which can either be stepped up or down by a transformer. A.c is produced when a conductor is rotated in a magnetic field or when a magnetic field is rotated near a conductor. This method is known […]
What is cathode rays?. These are streams of electrons emitted at the cathode of an evacuated tube containing an anode and a cathode. Production of cathode rays They are produced by a set up called a discharge tube where a high voltage source usually referred to as extra high tension (EHT) supply connected across a
What is a Len?. A lens is conventionally defined as a piece of glass which is used to focus or change the direction of a beam of light passing through it. They are mainly made of glass or plastic. Lens are used in making spectacles, cameras, cinema projectors, microscopes and telescopes. Types of thin lenses. A
Properties of waves Waves exhibit various properties which can be conveniently demonstrated using the ripple tank. It consists of a transparent tray filled with water and a white screen as the bottom. On top we have a source of light. A small electric motor (vibrator) is connected to cause the disturbance which produces waves. The
Centre of gravity Centre of gravity or C.G is the point of balance of a body in which the total weight of the body seems to act through. For regular shaped bodies the C.G is at the geometric centre of the body. For irregular bodies their weight still acts at the centre of the gravity
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Sound is an important example of a longitudinal wave which is composed of both compressions and rarefactions. The frequency range in which compressional disturbances occur is called the sonic spectrum and is very large. Sound is a range of compressional wave frequencies sensitive to human ear and is known as audio range which ranges from
Introduction Magnets are substances that are able to attract and hold items. Lodestone is the only known natural magnet which was discovered by the Chinese 2,000 years ago. Other magnets produced artificially by man are called artificia l magnets. Magnets and non-magnetic materials Magnetic materials are those that are strongly attracted by magnets while non-magnetic
Turning Effects The turning effect of a body is called the moment of that force. The turning effect produced depends on both the size of the force and the distance from the pivot. The moment of a force about a point is the product of the force applied and the perpendicular distance from the pivot
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X-rays were discovered by a German scientist named Roentgen in 1985. They can pass through most substances including soft tissues of the body but not through bones and most metals. They were named X-rays meaning ‘unknown rays’. X-ray production They are produced by modified discharge tubes called X-ray tubes. The cathode is in the form
Introduction Study of motion is divided into two; Kinematics Dynamics In kinematics forces causing motion are disregarded while dynamics deals with motion of objects and the forces causing them. Displacement Distance moved by a body in a specified direction is called displacement. It is denoted by letter‘s’ and has both magnitude and direction. Distance is
Force is a push or a pull. Force is therefore that which changes a body’s state of motion or shape. The SI unit for force is Newton (N). It is a vector quantity. It is represented by the following symbol. Types of forces Gravitational force–this is the force of attraction between two bodies of
States of matter Matter is anything that occupies space. Matter exists in three states: solids, liquids and gases. Matter can be changed in various ways which includes physical, chemical and nuclear changes. a) Physical changes– they are normally reversible and no new substances formed. Examples are; (i) Change of state such as melting and vaporization
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Energy This is the ability to do work. Forms of energy. Chemical energy: – this is found in foods, oils charcoal firewood etc. Mechanical energy:- there are two types; Potential energy – a body possesses potential energy due to its relative position or state Kinetic energy – energy possessed by a body due to its motion
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What is a wave?. A wave is simply a disturbance that moves through a medium . Other waves do not require a medium to travel i.e. they can travel in a vacuum, are known as electromagnetic waves e.g. radio, X-rays, gamma rays UV rays etc. Other waves require a material medium to be transferred and
Meaning of Radioactivity Radioactivity is the spontaneous disintegration or breaking down of the nucleus of an atom which makes it give out or emit radiation. Any element that disintegrates spontaneously and release rays us called a radioactive element Discovery of Radioactivity Radioactivity was discovered by a French physicist called Henri Becquerel in 1896. He
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FUNDAMENTALS OF MOTION Many scientists have studied motion and its properties because of its importance to life. The Italian, Galileo Galilei, who lived from 1564 to 1642, did the first systematic study of motion. The science of the study of motion done by Galileo is known as kinematics. Isaac Newton was another scientist who did
Machines make our work simpler. It is a force producing device by which a large force called load can be overcome by a small applied force called effort Terminologies Used In Machines FORCE RATIO (MECHANICAL ADVANTAGE ) VELOCITY RATIO EFFICIENCY MECHANICAL ADVANTAGE We define effort as the force applied to a machine and load as
DEFINITION OF FRICTION Friction (Fr) is defined as a force which acts at the surface of separation between two objects or two bodies in contact and tend to oppose the motion of one over the other. It is simply force of opposition. We have two types of friction: (a) Static friction, Fs (b) Dynamic friction,
MEANING OF PROJECTILE A projectile motion is one that follows a curved or parabolic path .It is due to two independent motions at right angle to each other .These motions are a horizontal constant velocity a vertical free fall due to gravity Examples of projectile motion are the motion of; a thrown rubber ball re-bouncing
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CONCEPT OF SCALAR AND VECTOR QUANTITIES Physical quantities are divided into scalar and vector quantities. A scalar is one which has only magnitude (size) e.g. distance, speed, temperature, volume, work, energy, power, mass etc. A vector quantity has both magnitude and direction e.g. force, weight, magnetic flux, electric fields, gravitational fields etc. VECTOR REPRESENTATION A
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