Electric Current and Its Effects Class 7 Extra Questions and Answers Science Chapter 14 PDF are solved by experts and will guide students in the right direction. Students can get how to tackle different questions easily by solving the Extra Questions for Class 7 Science Question bank on a regular basis.
Class 7 Science Chapter 14 Extra Questions and Answers Electric Current and Its Effects
Extra Questions for Class 7 Science Chapter 14 Electric Current and Its Effects with Answers
Electric Current and Its Effects Class 7 Extra Questions Very Short Answer Type
Question 1.
Which terminal of a cell is represented by longer line?
Answer:
Positive.
Question 2.
Where should be the key placed in a circuit?
Answer:
The key or switch can be placed anywhere in the circuit.
Question 3.
What is a filament?
Answer:
In the bulb there is a thin wire, called the filament, which glows when an electric current passes through it.
Question 4.
What is the full form of CFL?
Answer:
Compact Fluorescent Lamp.
Question 5.
What is the full form of MCB?
Answer:
Miniature Circuit Breaker.
Question 6.
Who discovered magnetic effect of electric current?
Answer:
Hans Christian Oersted.
Electric Current and Its Effects Class 7 Extra Questions Short Answer Type 1
Question 1.
What are complete and incomplete circuits?
Answer:
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 switeh is in the ‘OFF’ position, the circuit is incomplete. It is said to be open. No current flows through any part of the circuit.
Question 2.
Why should we not touch a lighted electric bulb connected to the mains?
Answer:
We should not touch a lighted electric bulb connected to the mains because it may be very hot and our hand may get burnt badly.
Question 3.
How does a fuse work?
Answer:
Every fuse is designed to carry current up to a certain maximum limit. If the current crosses that limit, the fuse wire melts due to heating effect of current and breaks the circuit. Thus, the circuit is saved.
Question 4.
What are the uses of electromagnets?
Answer:
- The electromagnets are also used to separate magnetic material from the junk.
- Doctors use tiny electromagnets to take out small pieces of magnetic material that have accidentally fallen in the eye.
- Many toys also have electromagnets inside them.
- Electromagnets are used in electric bells.
Electric Current and Its Effects Class 7 Extra Questions Short Answer Type 2
Question 1.
Discuss the reason for excessive currents in electrical circuits.
Answer:
(i) One reason for excessive currents in electrical circuits is the direct touching of wires. This may happen if the insulation on the wires has come off due to wear and tear. This may cause a short circuit.
(ii) Another reason for excessive current can be the connection of many devices to a single socket. This may cause overload in the circuit.
Electric Current and Its Effects Class 7 Extra Questions Long Answer Type
Question 1.
Write construction and working of an electric bell.
Answer:
Construction: It consists of a coil of wire 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.
Working: When the iron strip is in contact with the screw, the 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 breaks the circuit. The current through the coil stops flowing.
The coil is now 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 completed. This is how the bell rings.
Hope the knowledge provided regarding the Electric Current and Its Effects Class 7 Extra Questions and Answers has helped you to the possible extent. For more info feel free to reach us and we will guide you at the earliest possibility. Stay connected to our site to avail latest updates on Extra Questions for Various Classes instantly.