PHYSICS [2 Mark Question Answer]

The labeled diagram of a gold-leaf electroscope:

If the electrified silk cloth or the ebonite rod are brought near to each other then they will repel each other but when electrified silk cloth and glass rod are brought together then they attract each other. The charges on the electrified silk cloth and ebonite rod are negatives while on glass rod, it's positive so we can say that like charges repel each other while unlike charges attract each other.

The properties of an electric charge are
(1) Electric charges are quantized.
(2) Like charges repel each other while unlike charges attract each other.

Two differences between charge and mass are:
(i) Electric charge can be positive, negative, or zero while the mass of the body is strictly positive.
(ii) Electric charge is quantized while the quantization of mass is not yet established.

Suspend the iron bar and magnet freely in the space by using thread. And, move them here and there a few times. The bar which always points in north-south direction after coming to rest is a magnet and the other bar is the iron bar.

Suspend a magnet freely; it will always point towards the north-south direction. The pole of the magnet which points towards the north is called the north pole and the pole which points towards the south is called a south pole.

Artificial magnets are the magnets which are formed by bringing the natural magnet near it The artificial magnets have high retentivity means they remain magnetized for a long period of time and that is why they are used for making strong electromagnets.

Natural magnet is the deposits of the iron ore which has the attracting property of iron The properties of the natural magnet are :
(i) The magnet has the directive property when it is suspended freely, it always comes in a north-south direction.
(ii) A magnet attracts magnetic substances like iron, steel, etc. so, it has an attractive property.
(iii) Like poles repels each other while unlike poles attract each other in magnet.

When a positively charged rod is brought near the positively charged cap then, the positive charge on the cap will spread over because of repulsion and some of them will reach the leaves. Now, the leaves will have the same positive charge, they will repel each other and hence, leaves will diverge.

The functions of the bureau of energy efficiency setup are :
(1) control and keep an eye on consumption pattern
(2) develop appliances suitable for the energy change
(3) organize posters and slogans for developing awareness in society.

Improved practices in the use of energy :
(1) Use the improved cookstove which will save the bio-mass energy
(2) Use the improved solar panels and solar furnaces.

Disadvantages of setting up large dams for hydro-electricity power station::
(1) It leads to large catchment area being submerged
(2) displacement of people from their places.

If the magnetic material is brought near to the magnet then it gets attracted although it's not magnetized the magnetic material will be repelled only in case it is magnetised. So repulsion is the sure test of magnetism.

Two steel needles hanging from the lower end of the vertical bar magnet do not hang vertical but will diverge because they got the like poles on it and like poles repel each other so they diverge.

Soft iron is used to make electromagnets because it has high susceptibility and low retentivity, it gets magnetized very faster and loses magnetism as soon as the inducing magnet is removed.

The rubbed ebonite rod contains more electrons so it acquires the negative charge so a charge is acquired by it. But, in the rubbed metal rod, electrons are transferred but through hands and body, they pass to the earth so no charges will be there while the metal rod is held in hand.

When a nylon shirt, blouse, or stocking s are removed then they get rubbed with the hairs and due to friction between hairs and nylon, charges get induced on them and attractive force gets induced between them.

(i) If we had a magnet then we will bring the magnet near to steel, if there is a force of repulsion or attraction is experienced then steel was magnetized otherwise not.
(ii) We will hold the steel freely, if it points to north-south direction only then it is magnetized otherwise not.

Following are the properties of the magnet:
(i) Like poles of a magnet repel each other while unlike poles attract.
(ii) Magnet have an attractive property means it attract the magnetic material towards it.
(iii) Magnet have the directive property means when it is held freely, it always points towards north-south direction.

Primary cells are the cells in which chemical reaction is irreversible so they can't be charged again and again. While, secondary cells are the cells in which chemical reaction is reversible and can be charged again and again.

Differences between Conductor and insulators::
(a) Conductors allow the passing of electric current through it. Insulator does not allow the passing of current through it.
(b) Silver, Gold are good examples of the conductor of electricity. Rubber, Cotton are good examples of insulators.

Lightening conductor is a device used to safeguard the large buildings against the lightening of the thunderstorm. Normally, they are fitted on the top of tall buildings as a safety device. It consists of few metal spikes fitted to the highest part of the building and connected to thick copper strip which is buried inside the earth.

Electrostatic induction is the process of charging a body by bringing another charged body near to it. When the X will come near to body B, the opposite charge will be acquired by body B.
So, a negative charge will be acquired. Similarly, by electrostatic induction, A will acquire the opposite charge of B. so A will acquire a positive charge.

It will always rest in north-south direction. The diagram is as follows. The compass is telling that the magnet is pointing in a north-south direction.

We will start drawing the magnetic field of lines from the north pole of the magnet. When a small compass is placed at a point near the north pole of the magnet, the needle turns around on its pivot and settle in the fixed direction. At other points away from the pole the needle settles tangent to the drawn field line. By plotting the directions indicated by the needle, we can draw a magnetic field of lines.

The mechanism in which magnetism acquired by the magnetic material when kept near a magnet is called magnetic induction. When the magnetic material gets magnetized, the pole developed on its side will be opposite to the magnet's pole taken near to it. So, opposite poles attract each other. So, induction causes attraction.

The two usual shapes of the magnet are bar magnet and horse shoe magnet. The diagrams for bar magnet and horse shoe magnet are as follows :

The properties of the magnets are:
1.Attractive property
2.Directive property
3.Repulsive Properties

Voltmeter is used to measure the potential difference between two points in the circuit. Voltameter is an instrument for measuring the voltaic electricity passing through it, by its effect in decomposing water or some other chemical compound acting as an electrolyte.

The resistance of the wire depends on the following factors :
(i) Length of the wire
(ii) Cross-section of the wire
(iii) The temperature of the wire.
(iv) The material of the wire.

The two differences between primary and secondary cell are :
(a) Primary cells cannot be charged again while secondary cells can be charged again and again.
(b) In primary cells, a chemical reaction is irreversible while in secondary cells, a chemical reaction is reversible.

The two differences between primary and secondary cell are :
(a) Primary cells cannot be charged again while secondary cells can be charged again and again.
(b) In primary cells, a chemical reaction is irreversible while in secondary cells, a chemical reaction is reversible.

The factors on which resistance of the wire depends are :
(i) The length of the wire, resistance is directly proportional to the length of the wire.
(ii) The cross-section of the wire, resistance is inversely proportional to the cross-section of the wire.
(iii) The temperature of the wire, the resistance of wire is directly proportional to the temperature of the wire.
(iv) The material of the wire (good conductors possess less resistance.)

Rheostat symbol : It is used to control the current in the circuit.

Battery: It is used to charge the cell.

Key symbol : ; It is used to switch the current on or off in the circuit.

Voltmeter : ; It is used to measure the potential difference between two points of a circuit.

Ammeter : It is used to measure the current flowing through the circuit.

Cell symbol : ; It acts as a source of direct current for the circuit.

The electric resistance of the wire depends on the following factors :
(i)The length of the wire.
(ii)The area of cross-section of the wire.
(iii)The temperature of the wire.
(iv)The material of the wire.

A is a voltmeter to measure the potential difference,
B is an electric resistance to control the current in the circuit,
C is the ammeter to measure the magnitude of an electric current,
D is cell to provide electric current in circuit,
E is an electric key to on and off the circuit,
F is the rheostat to control the current in circuit.

Rheostat symbol :
It is used to control the current in the circuit.