UGC NET Paper 1 Mathematical Reasoning & Aptitude.pdf
Electric Current and Its effects.pdf
1.
2. ELECTRIC CIRCUIT
• Electric circuit is the path in which electric current flows
from a source across various components.
• Electric circuit diagram is the diagrammatic representation
of an electric circuit.
3.
4. ELECTRIC COMPONENTS
• The various parts/elements that are used to make an electric
circuit are called electric components.
• EXAMPLE–cell, battery, connecting wires, bulb, switch,
etc.
• Battery is a combination of two or more cells.
6. ELECTRIC SYMBOLS
• As it is cumbersome to show the electric components in a
circuit diagram, they are denoted or represented by specific
symbols . These are known as electric symbols.
7.
8. HEATING EFFECTS OF ELECTRIC
CURRENT
• Water heaters (geysers), electric irons, room heaters, etc. are
some electric devices in which heat is produced.
• Electricity produces heat, i.e. part of the electric energy is
converted into heat energy. This is called heating effects of
electric current.
10. HEATING ELEMENTS
• All appliances which produce on passing electricity are based
on the principle that heat is produced when electricity is
passed through a wire. This wire or coil of wire is known as
element/heating element.
• The amount of produced in a wire depends on the length
,thickness and the material of the wire.
11. • Good conductors are those which allow electricity to pass
through them.
• The amount of heat produced depends on how good or poor a
conductor the material of wire is.
• More heat is produced if the material of wire is nota
conductor.
• Hence ,heating elements are made up of materials which
have low conductivity or high resistance.
12. • Common materials used for heating element are tungsten and
nichrome.
• Nichrome is a material made up of nickel , iron and
chromium.
• The filament of an incandescent bulb is made up of tungsten.
• for this reason ,connecting wires , which are made up of
material like copper are not hot to touch.
14. EFFICIENCY OF ELECTRICAL APPLIANCES
• When electrical energy is partly converted into heat energy ,
it leads to wastage of energy in machines and appliance
where the heat is not utilised.
• Stars on electrical appliances indicate the efficiency or rating
of the appliances. More the number of stars , less is the
wastage of electrical energy.
15.
16. HOUSEHOLD SAFETY DEVICES
• There are two types of household devices:
1. Fuse
2. MCB(miniature circuit breaker)
18. 1. FUSE- a fuse is a household safety device which is based on
the principle of heating effects of electricity. A fuse consists of
a wire that breaks when high electricity is passed through it.
This can break can the circuit and prevent the current from
entering devices and causing damage to the devices and
possible fire.
2. MCB-MCBs are also safety devices used in households. Like
fuses ,MCBs too break the circuit or go off automatically by
overload in the circuit.
19. MAGNETIC EFFECTS OF ELECTRICITY
• A conducting wire behaves like a magnet when electricity is
passed through it and hence the needle in the magnetic
compass gets deflected.
• Factors on which magnetic effect of electric current depends-
1. It is directly proportional to the number of turns in the
coil.
2. It is directly proportional to the amount of current.
22. • USES-
1. They are used in devices and appliances like motors
,generators ,and loudspeakers ,hard disks , MRI machines
,etc.
2. They are used in magnetic levitation by which an object is
suspended with no support other than magnetic fields.
3. They are used for separating iron materials from junk. They
are used in separation of iron from ore.
4. They are used to magnetise and make permanent magnets.
23. ELECTRIC BELL
• An electric bell is based on the principle of electromagnetism.
24.
25. • CONSTRUCTION-
1. An electric bell consists of a curved iron rod mounted on a metallic strip ,a
switch , a hammer , a gong and a source of electricity.
2. The connecting wire is wounded over the iron rod so that it behaves like an
electromagnet when current passes through it.
3. One end of the wire is connected to a contact screw through a switch and a
source of electricity.
4. The end of the wire is connected to the lower end of the hammer, which is
called armature. This armature rests on the contact screw and a metallic gong
is placed in front of the hammer.
26. • WORKING-
1. When the switch is pressed on ,the current flows through the wire and the iron
rod becomes an electromagnet.
2. The electromagnet attracts the armature , and as the armature moves towards
the gong, it strikes the gong to produce sound.
3. Meanwhile, the connection between the armature and the contact screw breaks
,resulting in a break in the circuit.
4. Because of this ,the iron rod ceases to be an electromagnet and the armature
returns to the original position.
5. This process is repeated till the time he switch is kept in the on position.
