attractive property of magnets

The ability of magnets to attract magnetic materials to themselves

directive property

When freely suspended, you will notice that the magnet always rests in the north-south direction. This is because the magnetic field lines interact with the Earth's field lines.

magnetic strength

it is maximum at poles and minimum in the centre

attraction and repulsion

Like poles repel and unlike poles attract.

magnetic field

The imaginary lines around a magnet that attract magnetic material when they lie in the field. Its strength decreases with distance.

direction of magnetic field lines

they go from south to north

electromagnet definition

It is a temporary magnet created by passing electricity through a solenoid.

electromagnet components

it consists of a copper wire wound around a soft iron rod.

how to determine the polarity of an electromagnet

We can determine polarity by using the direction of the flow of power. the end where the current flows in the clockwise direction is the south pole and the end where the current flows in the counter- clockwise direction is the north pole.

How do we change the strength of an electromagnet

* we can increase or decrease the number of turns of the coil. * we can increase or decrease the power supply. * we can change the material of the item wrapped in the wire.

uses of electromagnets

* used to remove iron dust from wounds * used to load iron into hot furnaces * used in junkyards to collect iron scraps * used by doctors to detect and cure certain diseases

components of an electric bell

The negative terminal of the battery is connected to the adjustment screw. The positive terminal is connected to an electromagnet. facing the electromagnet, we have a soft iron armature that has a hammer at its end. The adjustment screw connects to the armature with a connecting spring.

working of electric bell

When the switch is turned on and the circuit is closed, the current flows to the electromagnet. The electromagnet attracts the armature, and the hammer at the end strikes the gong. When the armature moves, the circuit is broken, and the power supply to the electromagnet is cut off, and it loses its magnetism. Then, the electromagnet stops attracting the armature, and it goes back to its initial position.

static electricity

when particles are charged but do not moves

dynamic/ current electricity

when electric charges flow through a body.

how does the flow of charges take place

It takes place in the presence of the flow of electrons

what particles are involved in current

electrons are responsible of electricity, while protons are immobile

conventional current

current that goes from positive to negative

magnitude of current

amount of charge i= __________________ time

charge unit

coulomb

magnitude of electricity

ampere

primary cell

cannot be recharged. Most common type: dry cell

secondary cell

can be recharged. Most common type: wet cell

composition of a dry cell

consists of a zinc container that holds an electrolyte. The base of the container acts as the negative electrode. The carbon rod with a brass cap is placed in the centre of the cell, and this rod acts as the positive terminal. The rod is dipped in manganese dioxide and is placed inside a muslin bag. A moist paste of ammonium chloride surrounds the muslin bag.

CMAZ full form

C- carbon rod M- manganese dioxide A- ammonium chloride Z-zinc container

voltage of a dry cell

1.5 volts

why is a dry cell called so

it is called so as it uses moist pastes instead of liquid.

advantages of dry cell

* No risk of leakage * Easily transported * easily available

battery

a combination of 2 or more cells such that the positive terminal of 1 cell is attached to the negative terminal of the other.

secondary battery

also called accumulators or storage batteries.

electrolyte

a conducting liquid used in batteries

cathode

negative terminal

anode

positive terminal

shorting the battery

if 2 ends of a battery are connected without a device, it drains the battery.

resistor

an electrical device that regulates or resists the flow of current. a resistor reduces the flow of current.

electrical circuit

the path along which the current flows

switch/ key

device used to make or break the circuit.

galvanometer

used to detect the presence of electric current

ammeter

measures the electric current

voltmeter

measures the voltage of the current

series circuit

when the positive terminal of one battery connects to the negative terminal of another battery and so on, it forms a single path.

how do appliances work when connected to a series circuit

all the appliances work simultaneously, so if any one stops working, the circuit is broken.

parallel circuit

when all appliances share a common negative terminal and a common positive terminal such that they are parallel to the battery are are independent of each other.

precautions to be taken while connecting an electrical circuit

* Make sure the circuit is connected properly * never touch with wet hands * make sure the wires are properly insulated

conducting materials

silver, platinum, graphite, copper

insulating materials

wood, rubber, glass, plastic