Answer: Option C. -> heating effect
:
C
When an electric bulb is connected to a power source, electric current flows through the circuit. Flow of an electric current in a conductor generates a lot of heat due to the collisions between electrons and atoms. When current flows through the filament, it generates both heat and light. This happens due to the heating effect of electric current.

Answer: Option B. -> short circuit
:
B
The contact of live and fuse wire in a circuit is called short-circuiting. There is no current flow in this case.

Answer: Option C. -> magnetic effect of electric current
:
C
When electric current is passed through a conductor it behaves likea magnet. It is called an electromagnet.Working of an electromagnet is based on the magnetic effects of electric current.

Answer: Option B. -> H.C. Oersted
:
B
Hans C. Oerstedwas a Danish physicistand chemistwho discovered that electric currents create magnetic fields. This was the first instance to know about the connection between electricity and magnetism.

Answer: Option C. -> 6
:
C
Let the number of required cells be N. The total voltage is equal to 9 volt.
Therefore, $1.5\times N=9$
$N=\frac{9}{1.5}=6$
Hence6 cells will be required.

Answer: Option B. -> False
:
B
Electromagnets behave as magnets only when an electric current is passed through them. As soon as the current supply is switched off, it loses its magnetic properties. Magnetic materials like iron and steel are used to make electromagnets.

Answer: Option B. -> Free electrons
:
B
Metals are good conductors of electricity because they possessfree electrons. These free electrons help in the flow of current through the conductor.

Answer: Option C. -> force
:
C
The amount of heat produced in a conductor depends on the following parameters:
1.Material (resistance offered by the material) – good conductors produce less heat; e.g., elements of electric appliances are made of nichrome whereas connecting wires are made up of copper which is a better conductor so they do not get heated up easily.
2. Length – as length increases the heat produced also increases; e.g., heatingelementsare coiled in heaters to increase their length.
3. Thickness – as thickness increases the heat produced decreases; e.g., wires of iron are thicker than normal connecting wire so they don’t get heated up easily.
Force is not a parameter to be considered in this case.

Answer: Option C. -> force
:
B
Battery is a device with two or more electric cells connected in series.

:
Advantages: 2 Marks
Safe mark: 1 Mark
An incandescent bulb is used for light but it also gives too much of heat. This is not desirable. This results in the wastage of electricity. This wastage can be reduced by using fluorescent tube lights in place of the bulbs.
Compact fluorescent lamps (CFLs) also reduce wastage and can be fixed in the ordinary bulb holders.
CFLs are more efficient than filament bulbs in terms of energy consumption. The ISI mark ensures that the appliance is safe for use, reliable and is made up of good quality.