Electrical Energy – JSS3 Basic Science Lesson Note (Second Term)

Electrical energy is needed in industries, officers, and homes for carrying out numerous essential operations for instance blenders at home, televisions, irons, and fridges all use electrical energy to operate.

Electric current is the flow of electrons from one point to another in a circuit in a metallic conductor called a wires.

An electronic circuit is the path for the passage of electron current from a cell or battery to the lamp and back to the cell.

Simple electric circuit

An electric circuit is the path through which an electric current flows from a cell or battery to an appliance and back is the cell there are two major ways of connecting an electrical circuit

(1) In series connecting circuit elements are joined end so that saw current flows through each circuit element. Resistors in series total resistance R=R 1+ R2

(2) Connecting in parallel – the elements of the circuit are connected in such a way that the high potential terminals of two circuits are joined to one point and the two elements are joined to another point in the circuit

The arrangement ensures there is a uniform potential difference across the two elements where the current flow in them differs.

 Total Ressistance R =1/RI+1/R2

 Component of a circuit

The components of a circuit include the following

 (1) Resistor – This is in the form of wire or other materials used to reduce or resist a flow of current. It has a unit called ohms

(2) A lamp or bulb is used in a circuit to indicate the flow of electricity

(3) A switch is used in the circuit to put on or put off electric current

(4) Ammeter – is an instrument used to measure the amount of current following the unit is ampere (A)

(5) Voltmeter – is an instrument used to detect the flow of an electric current

(6) Galvanometer– is an instrument used to detect the flow of an electric current

(7) Fuse– is a piece of wire made of a tin-lead alloy having a low melting point it is used to cut off electric current when there is danger in the circuit

(8)Circuit breaker-This is a modern device that is introduced into the house circuit to increase safety in the use of electricity in the house.

Open circuit– This is a situation when an electric circuit does not conduct current because a switch is open i.e. a wire is broken.

Basic terms used in electricity

1. 1. Current is the flow of electrons along a conductor. The symbol is the ratio of the potential different (v) across the end of the conductor to the current I following through the conductor

R= V

     I

V= RXI

I = V / R

 ii. IV. Potential difference (pod) is the difference in the electrical potentials between the terminals of a cell or battery in a closed circuit

Iv Electromotive force (e.m. f ) is the electrical driving force between the terminals of a cell or battery in an open circuit

HOUSE CIRCUIT-Houses are wired in parallel because of some advantages of parallel circuits. One of the reasons is that if one bulb in the house is turned out, others will stay on. However, in a series circuit, all bulbs go off as soon as one of them burns out.

 Electric meter reading  and billing

An electric meter is a device that measures the amount of electric energy consumed by a residence, or industry by electric gadgets.

 ASSIGNMENT

1. The flow of current is usually in the opposite direction to the flow of   A.neutrons  B.protons  C.electrons  D.atoms
2. Electric circuits are connected in   _____ ways  A. four  B. two  C. three D. five
3. A voltmeter is an instrument for measuring  A.current  B.resistance  C.capacitance  D.potential difference.
4. What is the name of the electrical element in the house circuit that is used for connecting electrical appliances?  A.sockets  B.fuse box  C.control switch  circuit breaker
5. What is the name of the electrical element in the house circuit that is used for putting off the electricity supply anytime there is a repair or installation? A. sockets  B.fuse box control switch D. circuit breaker.
6. The amount of current flowing through an electric circuit is measured by   A. ammeter  B.ohmmeter  C. voltmeter  D. fuse 
7. The unit of measuring current is  A. ohm B. voltage  C.coulombs  D. ampere

7a. Mention four components of the electric circuit

b.Explain the term electric circuit

c.Mention two ways of connecting the electric circuit

1. what is the full meaning of   E. M . F