Tag: magnetic field due to a straight current carrying conductor

Questions Related to magnetic field due to a straight current carrying conductor

During a doorbell ringing

  1. Current always flows in the circuit

  2. Electromagnet is always present

  3. Striker is always in contact with metal gong

  4. Striker always repeatedly hits metal gong


Correct Option: D
Explanation:

Striker repeatedly hits the metal gong when doorbell is ringing. 

This can be observed in regular bells used at homes.

Armature is pulled towards the spring when it strikes the gong because

  1. The electromagnet gets demagnetized

  2. The current flow breaks

  3. Spring effect

  4. All of the above


Correct Option: D
Explanation:

The working of an electric magnet is based on the magnetic effect of current. When the key is pressed the circuit gets completed and current passes through it causing the electromagnet to get magnetized which in turn attracts the armature. This movement of the armature causes the hammer to strike the gong. However when the armature moves towards the gong the connection between the spring strip and adjusting screw is lost which breaks the circuit and the current flow is stopped thus demagnetizing the electromagnet. This causes the armature to return to its original position and it is thus pulled back due to the spring effect of the spring strip. This process is called a make and break circuit.

Which process is applied on a circuit for the working of an electric bell?

  1. Magnetization

  2. Make and break

  3. Both A and B

  4. None of the above


Correct Option: B
Explanation:

The working of an electric magnet is based on the magnetic effect of current. When the key is pressed the circuit gets completed and current passes through it causing the electromagnet to get magnetized which in turn attracts the armature. This movement of the armature causes the hammer to strike the gong. However when the armature moves towards the gong the connection between the spring strip and adjusting screw is lost which breaks the circuit and the current flow is stopped thus demagnetizing the electromagnet. This causes the armature to return to its original position and it is thus pulled back due to the spring effect of the spring strip. This process is called a make and break circuit.

The hammer hits the gong because

  1. It has electric charge

  2. It displays the spring effect

  3. It is attracted towards the electro-magnet

  4. All of the above


Correct Option: C
Explanation:

The working of an electric magnet is based on the magnetic effect of current. When the key is pressed the circuit gets completed and current passes through it causing the electromagnet to get magnetized which in turn attracts the armature. This movement of the armature causes the hammer to strike the gong.

A moving charge produces

  1. Neither electric field nor magnetic field

  2. Electro-static field only

  3. Magnetic field only

  4. Both magnetic and electro-static field


Correct Option: D
Explanation:

A charged particle produces an electric field around it independent of its motion. But when it is at rest, it doesn't produce a magnetic field. 

When it starts moving, it additionally produces a magnetic field too.

The strength and direction of the magnetic field depends on ..........

  1. Magnitude of electric current

  2. Direction of electric current

  3. Both A and B

  4. None of the above


Correct Option: C
Explanation:

In his experiment Oersted observed that the deflection of the needle compass changed according to the direction of the current and also as the current in the wire increased, the deflection of the needle increased. Thus he inferred that the strength and direction of the magnetic field depends on the magnitude and direction of current.

Which of the following effects of current does not depend on the direction of current?

  1. Lighting and chemical effects

  2. Heating and lighting effects

  3. Heating and magnetic effects

  4. Magnetic and chemical effects


Correct Option: B
Explanation:

Heating effect and lighting effect does not depend on the direction of current.

What inferences were drawn from Oersteds experiment?

  1. A current or a moving charge produces magnetic field around it

  2. Presence of magnetic field can be detected using a compass needle

  3. The strength and direction of the magnetic field depends on the magnitude and direction of the current

  4. All of the above


Correct Option: D
Explanation:

Oersted conducted an experiment to study the magnetic effect of electric current. In this experiment he observed the deflections of a compass needle placed in close proximity of an electric wire carrying current. He observed that in the absence of current the needle came to rest in Earths North-south direction under the influence of Earths magnetic field. However, when the needle was kept in close proximity of an electric wire carrying current it showed deflections in the east and west direction depending on the direction of current. Thus, indicating that the strength and direction of the magnetic field depends on the magnitude and direction of the current.

The magnitude of current is ........ the magnitude of magnetic field

  1. Inversely proportional to

  2. Directly proportional to

  3. Same as

  4. None of the above


Correct Option: B
Explanation:

In his experiment Oersted observed that as the current in the wire increased, the deflection of the needle also increased, indicating that they are directly proportional.