Answer: Option A. -> Fuse wire
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A
A fuse is a short length of wire designed to break the circuit in case of excessive current. Temperature increases with current, and after a point the fuse melts thereby breaking the circuit. Fuse wire is made up of a material which has low melting point, thereby saving electrical applicances from damage.

Answer: Option C. -> Bulb
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C
The above symbol is used to represent a bulb in an electric circuit.
An electric bulb consists of a transparent glass casing containing a wire filament (usually tungsten) that emits light due to the heating effect of electricity.

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Part (a): 2Marks
Part (b): 1 Marks
(a)
1. When an electric current is passed through the conductor, electrons collide with nearby electrons more frequently, which produce heating effect.
3. The increase in kineticenergy of atoms give rises to heat energy, which gives heating effect when current passes through the conductor.
(b) Toaster and electric geyser

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The function of filament: 1Mark
The principle: 1 Mark
The thin wire in an electric bulb that gives off light is called the filament. Due to the high resistance of the filament and heating effect of electric current, filament glows and gives us light.
The working of the bulb is based on the principle of the heating effect of electric current.

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Part (a) : 3 Marks
Part (b): 2 Marks
(a) No, the bulb will not glow in this circuit because the switch is open and the circuit is incomplete.
Whenever we have an open circuit no current flows through it.
So, to light the bulb we can complete the circuit by putting any conductor connecting the two terminals.
We can use a metallic wire to close the open circuit.When we put a metallic wire the bulb will light up.
(b)When a bulb gets fused, its filament is broken that breaks the circuit and the flow of current stops.
The filament is made up of wire with high melting point like tungsten.
A filament is partof the light bulb that produces light.

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Explanation: 1 Mark
Diagram: 1 Mark

The positive terminals of the cell will be connected to negative terminal of the cell and vice versa with the wire to make it a battery.

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Part (a) : 2 Marks
Part (b) : 1 Mark
(a) MCB stands forMiniature circuit breakers.
MCBs are basically a substitute for fuses.These are switches which automatically turn off when the current in a circuit exceeds the safe limit. We turn them on and the circuit is once again complete.
They are preferredover fuses because they are much more user-friendly, because if there is excess current in the circuit they automatically turn off, and the circuit is complete again if we turn it on. While in afuse, the fuse has to be replaced once excess current passes through it.
(b)Electric fuse works on the principle of the heating effect of current.

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Definition: 1 Mark
Formation and uses: 2 Marks
A combination of two or more cells connected together is called a battery. It supplies electric current.
It is formed by connecting the positive terminal of one cell to the negative terminal of another. Positive and negative terminalsare denoted as + and -respectively.
These batteries are used in many devices, such as torch lights, mobile phones, calculators and even automobiles.

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Explanation: 2 Marks
The magnetic field at any point can be in one direction only. If two magnetic lines of forceintersect each other, at the point of intersection there will be two different directions of the magnetic field, which is not possible.

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Explanation: 3 Marks
Diagram: 2 Marks
An electromagnet is a soft iron core made into a magnet by the passage of electric current through a coil surrounding it. The coil in the above activity behaves like a magnet when electric current flows through it. When the electric current is switched off, the coil generally loses its magnetism. Such coils are called electromagnets. The electromagnets can be made very strong and can be used to lift very heavy loads.