Magnetism

Question 1

Unit of magnetic field

Answer 1

Tesla

Question 2

The number of magnetic field lines passing through a given area

Answer 2

Magnetic flux

Question 3

Unit of magnetic flux

Answer 3

Weber wb

Question 4

The number of magnetic field lines crossing unit area kept normal to the direction of field lines is called

Answer 4

Magnetic flux density
Unit of magnetic flux density wb/m2

Question 5

The current carrying conductor produce magnetic field around it is demonstrated by

Answer 5

Hans Christian oersted

Question 6

Who found that a charge moving in a magnetic field in a direction other than the direction of magnetic field experiences A Force

Answer 6

H a Lorentz
It is called the magnetic Lorentz force

Question 7

In 1821 who discovered that the current carrying conductor also get reflected when it is placed in a magnetic field

Answer 7

Michael Faraday

Question 8

1 When the conductor is parallel to the magnetic field the force will be
2 when it is parallel to the magnetic field the force will be

Answer 8

Maximum
Zero
F= BIL
B MAGNETIC FIELD
I CURRENT
L. LENGTH OF THE CONDUCTOR
The angle of inclination between the current and magnetic field also affect the magnetic field
Force is always a vector quantity

Question 9

Fleming left hand rule is also known as

Answer 9

Motor rule
The direction of current is denoted by the middle finger of the left hand and the second finger is for direction of the magnetic field then the thumb of the left hand denote the direction of force or movement of the conductor
Three fingers of left hand in perpendicular to each other

Question 10

To change the direction of current in DC motor a small device called

Answer 10

Split ring commutator

Question 11

The speed of rotation of coill can increased by

Answer 11

Increase in the strength of current in the coil
increase in the number of terms in the coil
increase in the area of the coil
increasing the strength of the magnetic field

Question 12

In which year Michael Faraday explained the possibility of producing EMF across the conductor when the magnetic flux linked with the conductor is changed

Answer 12

1831

Question 13

The phenomenon of producing an induce EMF due to change in the magnetic flux linked with a closed circuit is known as

Answer 13

Electromagnetic induction

Question 14

The direction of the induced current was given by

Answer 14

Lenz law state that the induced current in a coil flows in such a direction has to oppose the change that causes it. கம்பிச்சுருளில் தூண்டப்பட்ட மின்னோட்டமானது அது உருவாக காரணமாக இருந்த காந்தபாய மாற்றத்தை எதிர்க்கும் என்பது லென்ஸின் விதி ஆகும்
The direction of induced current can also be given by another rule called flemings right hand rule

Question 15

Michael Faraday main discoveries

Answer 15

Electromagnetic induction diamagnetism, electrolysis

Question 16

Fleming right hand rule is also called

Answer 16

Generator rule
Middle finger direction of induced current (direction of current in left hand rule)
Thumb finger indicates direction of motion of conductor(direction of force or moment of conductor in left and rule)
Fore finger direction of magnetic field

Question 17

Transformer work on the principle of

Answer 17

Electromagnetic induction

Question 18

Formula of transformer

Answer 18

Np/Ns = Vp/Vs = Is/Ip

Question 19

Transformer cannot be used with the direct current source

Answer 19

Because the current in the primary coil is constant in DC. Then there will be no change in the number of magnetic field lines linked with the secondary coil and hence no EMF will be induced in the secondary coil

Question 20

The magnetic field setup by a current carrying conductor is always at _________ to the direction of flow of current

Answer 20

Right angle