Electricity and Magnetism

51問 • 2年前

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– is defined as the study of electricity at rest. Static electricity involves electric charges. Electric charges arise from particles of atoms.

Electrostatics

•Atoms have electric charges inside them. In the center of each atom is the —. This is made up of — and —. In the outer part of the atom are found the orbiting —

nucleus protons and neutrons (positive and neutral) electrons (negative)

RUBBING two different kinds of MATERIALS against each other may cause the — from one material to another. This upsets the balance between the positive and negative charges.

transfer of electrons

The repulsive and attractive forces follow the — that states that LIKE CHARGES REPEL and UNLIKE CHARGES ATTRACT

law of electric charges

The PRESENCE of excess ELECTRIC charge can be DETECTED by an .

electroscope

Electric charges are more easily moved in some materials. This characteristic led to the classification of materials into: — where charges are free to move, — where charges are not free to move.

conductors, insulators

Another kind of material that is somewhere between insulators and conductors is called a —.

semiconductor

Certain materials known as — become perfect conductors at very low temperature.

superconductors

Conductors can be charged by —.

conduction

is the transfer of electrons from charged object to another object by direct contact.

Conduction

is the MOVEMENT of ELECTRONS to one part to one part of the object BY the ELECTRIC FIELD of another object.

Induction

In induction process, the — type of charge is produced.

opposite

Induction process However, even in insulator, effect ; ELECTRIC CHARGES can SHIFT slightly to ONE SIDE when there is a charge nearby

polarization

COULOMB’S LAW states that the force of ATTRACTION or REPULSION between two small charged bodies is DP; to the — IP: to the — between them.

PRODUCT of the TWO CHARGES SQUARE of the DISTANCE

The standard unit for charge is called

coulomb C.

It is defined as the AMOUNT OF CHARGE TRANSFERRED through a POINT on a CONDUCTOR in ONE SECOND by a current of one AMPERE.

Coulomb

F = Q =

F = k q1q2/d2 Q = It

is the movement of charged particles in a specific direction.

Electric current

The charged particle may be an electron, a positive ion or a negative ion, and they are referred to as —.

current carriers

The symbol used for current is

is the measure of how much charge is passed through a given point in a conductor per given amount of time.

Current

The unit of current is given in — and is named —

coulomb per second (C/s), ampere (A)

current = I =

current = charge/time I = q/t

•If the current continues to flow in the SAME DIRECTION through the conducting wire all the time, it is called —.

direct current

This is the kind of current that we get from flashlight cells and batteries.

Direct current

If the current periodically REVERSES THE DIRECTION in which it is moving, it is called —.

alternating current

This is the kind of current we have in our home, schools and other institutions.

Alternating current

—, which is AKA — or potential difference is the ELECTRIC PRESSURE that causes current to flow.

Voltage, electromotive force (emf)

Potential difference is potential energy divided by —.

charge

The symbol for voltage is The unit of voltage is the — which is called the —.

V joule per coulomb, volt

voltage = V =

voltage = energy/charge V = W/q

Devices such as an electric generator, electric cell, thermocouples, crystals and solar cells produce —.

voltage

— is the opposition a material offers to current.

Resistance

The symbol for resistance is —.

All materials offer some resistance to current but the amount of resistance differs from each other. The unit used to specify the amount of resistance is the —, represented by the symbol of —.

ohm, omega

The — is defined as the amount of resistance that allows 1 A of current to flow when the voltage is 1 V.

ohm

•Resistance of on object depends on four factors

LCRT 1) length, 2) cross-sectional area, 3) resistivity of the material and 4) temperature.

•The amount of resistance of an object is DIRECTLY proportional to its — and INVERSELY proportional to its —

length, cross sectional area.

R = A =

R = pL/A A = πd2/4

It is stated as, current is directly proportional to the — and inversely proportional to the —.

voltage, resistance

The — which measures current in — The — which measures resistance in — The — which measures voltage in —.

ammeter, amperes ohmmeter, ohms voltmeter, volts

is the rate of energy transfer.

Power

Power is equal to the PRODUCT of the

CURRENT and VOLTAGE.

The unit of POWER is the - when voltage is in VOLTS and current is in AMPERES

watt

•— is equal to power times time.

Energy

Energy can also be expressed using —3

current, voltage and time.

— has two or more loads but current flows through a SINGLE CONDUCTING PATH

series circuit

In a SERIES circuit, if any of the CIRCUIT IS OPEN, — STOPS FLOWING and —2 are REMOVE from all loads.

CURRENT VOLTAGE and POWER

A — has MORE THAN ONE for current to flow.

parallel circuit

A parallel circuit ALLOWS OPERATION of other loads even if —.

one load fails

Some resistors are arranged in a COMBINATION of both SERIES AND PARALLEL CIRCUITS, and of DIFFERENT ELECTROMOTIVE forces. These COMPLEX CIRCUITS are called —.

networks

KEY TERMS

Guillermo, Rizchel Anne B. · 17問 · 2年前

KEY TERMS