Quiz sheet for electromagnetism

If the number of turns on a coil is doubled the magnetic flux will:

A) increase

B) decrease

C) remain constant

D) fall to zero

ANSWER: A

The magnetic field surrounding a conductor can be increased by:

A) using a conductor of smaller diameter

B) increasing the temperature of the conductor

C) increasing the current flowing in the conductor

D) changing the type of conductor insulation

ANSWER: C

The magnetomotive force of a magnetic circuit is determined by the:

A) The number of turns on the coil divided by the current flowing in the coil.

B) Resistance of the coil.

C) application of the circuit.

D) the number of turns on the coil multiplied by the current flowing in the coil.

ANSWER: D

Soft iron and silicon iron alloys are used in electromagnets because they have high:

A) Permeabilty

B) Voltage rating

C) Reluctance

D) Strength

ANSWER: A

The ability of a material to retain its magnetic flux is called: 

A) residual

B) reluctance

C) retentivity

D) permeability

ANSWER: C

The concentration of flux in a given area is called: 

A) Magnetizing Force

B) Flux Density

C) Magnetic Flux

D) Flux Concentration

ANSWER: B

The material best suited for the core of an electromagnet is: 

A) carbon

B) manganin

C) copper

D) steel

ANSWER: D

The opposition to the magnetic flux is called: 

A) resistance

B) residual

C) residual

D) reluctance

ANSWER: D

The purpose of magnetic screening is to: 

A) screen outside influences from a magnetic field

B) shield equipment from a magnetic field

C) screen current from a magnetic field

D) use a non-magnetic material as the screening material

ANSWER: B

The magnetic lines of flux associated with a bar magnet:

A) enter at the south pole and leave at the north pole

B) are strongest at the south pole

C) are weakest inside the magnet

D) flow from the south pole to the north pole

ANSWER: A

To reduce hysteresis, core materials should be made from:

A) carbon steel

B) copper

C) stainless steel

D) silicon steel

ANSWER: D

The ability of a material to accept a magnetic field is called its: 

A) retentivity

B) reluctance

C) permeabilty

D) resistance

ANSWER: C

Using the right hand rule for solenoids,  the fingers indicate the direction of:

A) current

B) motion

C) magnetic field

D) velocity

ANSWER: A

Magnetic fringing will produce an:

A) increase in flux density in the air gap

B) increase in the magnetomotive force in the magnetic circuit

C) decrease in flux density in the air gap

D) decrease in the magnetomotive force in the magnetic circuit

ANSWER: C

The direction of a magnetic field produced by a solenoid may be reversed by:

A) Current

B) Resistance

C) Reluctance

D) Magnet

ANSWER: A

Using the right hand rule for solenoids,  the thumb indicates the direction of:

A) current

B) motion

C) magnetic field

D) velocity

ANSWER: C

The ability of a material to oppose a magnetic field is called its: 

A) retentivity

B) reluctance

C) permeabilty

D) resistance

ANSWER: B

Magnetising force is:

A) reluctance per unit length

B) current x turns รท length

C) pressure exerted by a magnet

D) force between north and south pole of a magnet

ANSWER: B

An electromagnet is

A) temporary

B) permanent

C) insulator

D) conductor

ANSWER: A

Direction of magnetic field is governed by direction of

A) current

B) voltage

C) both Voltage and EMF

D) EMF

ANSWER: A

If two single current carrying conductors adjacent to each other have currents flowing through them in opposite directions, then a/an ______ force exists between the two coils.

A) repulsion.

B) attraction.

C) magneto motive

D) inductive.

ANSWER: A

In a single current carrying conductor, current flowing towards the viewer can be shown by a ______

A) dot

B) cross

C) asterisk

D) zero

ANSWER: A

If a mild steel core is inserted into an air cored coil, the inductance will ______ due to an increase in the ______.

A) increase; permeability of the flux path

B) increase; magnetomotive force of the flux path

C) decrease; reluctance of the flux path

D) decrease; length of the iron core

ANSWER: A

The B-H curve which is shown as a straight line would be that for:

A) air

B) cast iron

C) mild steel

D) silicon steel

ANSWER: A

The flux surrounding a coil is ______ to the reluctance of the core.

A) inversely proportional,

B) proportional,

C) equal

D) tangental

ANSWER: A

The magnetic field surrounding a single current carrying conductor is:

A) circular and dependent of the direction of current flow.

B) circular and independent of the direction of current flow.

C) axial and independent of the direction of current flow.

D) axial and dependent of the direction of current flow.

ANSWER: A

The opposition of a material to becoming magnetised is known as:

A) reluctance.

B) impedance.

C) resistance.

D) inductance.

ANSWER: A

Compared to the inductance of a straight conductor, the inductance of an air cored coil will be:

A) greater

B) equal

C) less

D) zero

ANSWER: A

In a magnetic circuit, reluctance is _____ to the length of the core.

A) proportional

B) inversely propor*

C) equal

D) across

ANSWER: A

The flux set up by a coil depends on the mmf produced by the coil and ______ of the iron core:

A) reluctance.

B) C.S.A.

C) magnetising force.

D) flux density.

ANSWER: A

When a current passes through a conductor, it produces

A) magnetic field

B) electric field

C) electromagnetic field

D) mechanical field

ANSWER: A


Last modified: Tuesday, 1 June 2021, 9:42 AM