Electricity Magnetic and Heating Effects Class 8 Short Question Answer

Electricity Magnetic and Heating Effects Class 8 Short Question Answer

Electricity Magnetic and Heating Effects Class 8 Short Question Answer

Question 1.

What happens to an iron nail wrapped with a wire when an electric current flows through it?

Answer:

The iron nail becomes an electromagnet and can pick up magnetic materials like paper clips.

Question 2.

Why does the LED glow in a Voltaic cell made with lemons and metal electrodes?

Answer:

The LED glows because the chemical reaction between the metals and the lemon juice generates an electric current.

Question 3.

What is the effect of increasing the number of turns in a coil connected to a current source on the strength of the electromagnet?

Answer:

Increasing the number of turns in the coil enhances the strength of the electromagnet.

Question 4.

Why does the lifting electromagnet stop working after some time, even if the circuit remains closed?

Answer:

The lifting electromagnet may stop working due to overheating or a drop in current, which can occur if the wire becomes too warm and resistance increases.

Question 5.

What is the role of the electrolyte in a Voltaic cell?

Answer:

The electrolyte facilitates the chemical reaction between the electrodes, allowing the flow of electric current.

Question 6.

What is the magnetic effect of electric current, and how can it be demonstrated using a simple experiment?

Answer:

The magnetic effect of electric current refers to the phenomenon where an electric current flowing through a conductor generates a magnetic field around it. This can be demonstrated by placing a magnetic compass near a wire carrying current; the compass needle will deflect, indicating the presence of a magnetic field.

Question 7.

Explain how an electromagnet is formed and its practical applications.

Answer:

An electromagnet is formed by wrapping a coil of wire around an iron core and passing an electric current through the wire, which magnetises the iron core. Electromagnets are widely used in applications such as electric motors, magnetic locks, and lifting devices due to their ability to be turned on and off.

Question 8.

What is the heating effect of electric current, and why is nichrome wire commonly used in heating devices?

Answer:

The heating effect of electric current occurs when electric current flows through a conductor, causing it to generate heat due to resistance. Nichrome wire is commonly used in heating devices because it has a high resistance, allowing it to generate more heat for a given current while being durable and resistant to oxidation.

Question 9.

How can we determine if a battery is dead, and what are the characteristics of rechargeable batteries?

Answer:

A battery can be determined to be dead if it no longer provides sufficient voltage to power a device or if it shows a significant drop in performance. Rechargeable batteries can be recharged and reused multiple times, making them more economical and environment friendly compared to single-use batteries.