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Reason: 2 Marks
When current is passed through a wire it starts behaving as a magnet. This happens due to the magnetic effect of electric current.
Hence, when a compass needle is placed near the given current carrying wire, it gets influenced by the magnetic effect of electric current and gets deflected from its North-South position.

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Working of electric bell: 3 Marks
The coil is no longer an electromagnet. It no longer attracts the iron strip.
The iron strip comes back to its original position and touches the contact screw again. This completes the circuit. The current flows in the coil and the hammer strikes the gong again. This process is repeated in quick succession.
The hammer strikes the gong every time the circuit is complete.
This is how an electric bell rings. The continuous breaking and completing of the circuit enable the gong to strike the hammer continuously.

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Components: 2 Mark
Working: 3 Marks
An electric bell consists of a coil of wire. An electromagnet wound on an iron piece. The coil acts as an electromagnet.
An iron strip with a hammer at one end is kept close to the electromagnet.There is a contact screw near the iron strip.
When the iron strip is in contact with the screw, current flows through the coil which becomes an electromagnet.
It, then,pulls the iron strip. In the process, the hammer at the end of the strip strikes the gong of the bell to produce a sound.
However, when the electromagnet pulls the iron strip, it also breaks the circuit. The current through the coil stops flowing and it isno longer an electromagnet. It no longer attracts the iron strip.The iron strip comes back to its original position and touches the contact screw again.
This completes the circuit. The current flows in the coil and the hammer strikes the gong again.
This process is repeated in quick succession.The hammer strikes the gong every time the circuit is complete. This is how the bell rings.

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Explanation: 2 Marks
A switch is a device used to make or break an electric circuit.When the switch is in the ‘ON’ position, the circuit from the positive terminal of the battery to the negative terminal is complete. The circuit is then said to be closed and the current flows throughout the circuit instantly.
When the switch is in the ‘OFF’ position, the circuit is incomplete. It is said to be open. No current flows through any part of the circuit.

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Each point: 1.5 Mark
1. When electric current flows through a wire, the wire gets heated. It is the heating effect of current or when current flows through a metal wire it gets heated up, this is called the heating effect of current. E.g. a glowing electric bulb becomes warm. This effect has many applications like Electric Heater, Light Bulb etc.
2. When an electric current flows through a wire, it produces magnetic effect around it. A current-carrying coil of an insulated wire wrapped around a piece of iron isan electromagnet. Magnetic effect of electric current has many applications like and is used in many objects like, electric bell, motor, fan etc

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Each point: 1 Mark
$\begin{array}{cc}Electromagnet& Permanentmagnet\\ 1.Itisatemporarymagnetandcanbedemagnetized& 1.Itisapermanentmagnetandcannotbedemagnetizedeasily\\ 2.Magneticstrengthcanbechanged& 2.Itsstrengthisfixed\\ 3.Itspolaritycanalsobechanged& 3.Itspolarityisfixed\\ 4.Itispreparedfromsoftiron& 4.Itispreparedfromhardsteel\\ 5.Directionofmagneticfieldcanbereversed& 5.Directionofmagneticfieldcannotbereversed\\ 6.Magneticfieldisproducedwhenelectriccurrentflows.& 6.Electriccurrentisnotrequiredtoproducemagneticfield.\end{array}$

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Explanation: 1.5 Marks
Diagram: 1.5 Marks
In the fig., one end of the bulb is connected to the battery while theother end is connected with a safety pin which is a conductor. However, the other end battery is not connected with the safety pin which was required for the current to flow. Thus, the switch is in off position or circuit is not complete.
So the bulb will not glow.

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Factors: 0.5 Mark each
Working Principle: 1 Mark
The factors on which the amount of heat produced in a wire depends are:
1) its material
2) length of the wire
3) the thickness of the wire
4) the amount of current passing through the wire
The working of an electric bulb is based on the principle of the heating effect of electric current.

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Naming: 1 Mark
Function: 1 Mark
Fuses are used as safety devices.
Fuses ensure that excessive current does not flow in the electric circuit. If excessivecurrent flows in the electric circuit it may cause damage to the electric appliances.
There is a maximum limit on the current which can safely flow through a circuit. If by accident the current exceeds this safe limit, the wires may become overheated and may cause fire.

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Working Principle: 1.5 Marks
Factors: 1.5 Marks
Electric heater works on the principle of the heating effect of electric current. When an electric current is passed through the coil of the heater, it becomes hot. The coil ofwire is called an element.
The factors on which the amount of heat produceddepends on are:
1) the material of the coil
2) the length and thickness of the wire
3) the amount of current passing through the wire