Electromagnet

Q.

What are the four Ways to Make an Electromagnet Stronger?

Q. We can increase the strength of an electromagnet by increasing the number of turns of wire on the coil and but is there any other method with the help of which we can increase the strength of an electromagnet?

1. by increasing the flow of current

2. by increasing the thickness of wire

3. by decreasing the flow of current

4. by increasing the thickness of magnet

Q.

What is the working principle of electromagnet?

Q.

Who first discovered the magnetic effect of electricity?

Q.

State three ways by which the strength of an electromagnet can be increased?

Q.

For making an electromagnet the best material to be used is

1. stainless steel

2. silver

3. soft iron

4. nickel

Q. Which of the following statements are true about the electromagnets?

1. Their polarity can be reversed.
2. Their magnetic strength cannot be altered.
3. Electric current is the main source for their magnetism.
4. They are temporary magnets.

Q. Electric bell works on the heating effect of electric current.

1. True
2. False

Q.

Can we use an electromagnet for separating plastic bags from a garbage heap?

Q. How can we increase the magnetic field of an electromagnet?
Explain each method.

Q.

How can you reverse the poles of an electromagnet?

Q. The strength of an electromagnet cannot be increased by

1. increasing current in the coil.
2. increasing the number of turns in the coil.
3. reversing polarity of the battery.
4. using core of larger cross-section.

Q.

Mention two uses or applications of a solenoid.

Q.

Which of the following uses an electromagnet as its main component?

1. Electric bell

2. Electric fan

3. Electric cell

4. Electric motor

Q. Which of the following metal nails is best suited to make an electromagnet?

1. 
   Copper nail
2. 
   Aluminium nail
3. 
   Soft iron nail
4. 
   Steel nail

Q.

Give a reason for the following.

An electromagnet loses its magnetism when the current flowing through its coil is stopped.

Q.

What is an electromagnet? Give two methods by which we can increase the strength of magnetic field produced by a circular coil carrying current? [4 MARKS]

Q. Do you think an electromagnet can be used for separating plastic bags from a garbage heap? Can it be used to separate scrap iron from the heap? Explain. [3 MARKS]

Q.

An electromagnet is based on the heating effect of current.

1. True
2. False

Q. Which of the following statements is NOT true about an electromagnet?

1. An insulated wire is wound around it.
2. It is used in fans and radios.
3. It works only in the presence of electricity.
4. It is a permanent magnet.

Q.

How one can change the deflection of a magnetic needle that has been kept near a current carrying wire of a circuit?

1. By changing the direction of current.

2. By changing the wiring of the circuit.

3. By changing the cell.

4. By changing the material of the needle.

Q. Can an electromagnet be used to separate metals from other magnetic metals?

Q.

An electromagnet acts as a standard magnet only when there is an electric current.

1. False

2. True

Q. Which of the following statements is incorrect regarding an electromagnet?

1. Their magnetic strength can be altered.
2. They can be turned on and off.
3. They are permanent in nature.
4. They have both North and South Poles.

Q. Which of the following is true about current carrying conductors?

1. They behave as magnets always.
2. They can never behave as a magnet.
3. A coil of the current carrying conductor behaves like a magnet.
4. A current carrying conductor is always attracted to a magnet.

Q.

A magnet that is made by passing electric current through a coil surrounding a metal core is called an _____________.

Q.

The magnetic effect of the electric current was first observed by ___.

1. Isaac Newton

2. Galileo Galilei

3. H.C. Oersted

4. W.H. Whitkar

Q. Why does a magnetic needle gets deflected when brought near a current carrying?

Q.

What do you mean by electromagnet ? [2 marks]

Q.

If a bar of steel is placed in a solenoid, then it changes to ______.

1. an electric bell

2. an electromagnet

3. a dynamo

4. a permanent magnet