Class 7 Science Chapter 10 Question Answers - Electric Current and Its Effects

Q1. Explain the function of the electrical fuse in a circuit.
Ans: Fuse is made up of material having low melting point. The main function of a fuse is to break the circuit if there is overflow of current and prevent fire. The fuse protects electrical wires and appliances from damage from excess current.

Q2. What is MCB? What is its Function?
Ans: MCB is the abbreviation for Miniature Circuit Breaker. It is a tool that is used in place of a fuse. MBC automatically breaks the circuit if it exceeds the safe limit of current passing through it to prevent fire and other damage. MCB can be turned on manually

Q3. Give an example to show that we use the heating effect of electric current in our daily lives.
Ans: The use of heaters and geysers is an example of the heating impact of electric current. These instruments contain a thick coil of wire called heating elements. When electricity is passed through them these wires start glowing red and produce heat. Hence, heat is generated with the help of electric current.

Q4. Why does an electric bulb get fused?
Ans: A filament is an extremely tiny wire found within an electric bulb. When electricity is passed through a filament, it heats up and glows, emitting light. The filament, on the other hand, is a thin wire. When too much electric current is passed through the filament, or when it is passed through the filament repeatedly, it becomes too hot and breaks. This results in fusing of the bulb.

Q5. Draw the circuit diagram for the following circuit.

Ans: Below is the circuit diagram:

Q6. What is an electromagnet?
Ans: An electromagnet is a temporary magnet that is formed because of the magnetic effect of electric current. When electric current passes through a wire it behaves like a magnet. The strength of an electromagnet depends on the amount of current passing through it. Electromagnets show all the property of a magnet such as:

• Attractive Properties
• Repulsive Properties
• They also point in a north-south direction when suspended freely.

Electromagnets are used in large cranes in junkyards to separate iron or any other magnetic object from the garbage.

Q7. Explain the working of an electric bell.
Ans:

The electric bell consists of a coil of wire wound around a magnetic material like iron. The iron material is connected to a hammer at one end and a screw at the other end.

• When we press the switch electric current flows through the coil and iron core gets magnetised and behaves as electromagnet.
• Magnetic field created by this iron pulls the clapper towards themselves.
• As a response the clapper strikes the gong and we hear the ringing of a bell.
• The striking of gong breaks the circuit and the magnetic field is lost.
• The clapper returns to its original place.
• This process is repeated every time we switch it on and current flows through the circuit.