Moving charges and magnetism

Question 1

The magnetic effect of electric current was discovered by :

Answer 1

Oersted

Question 2

A moving charge produces

Answer 2

Both electric and magnetic field

Question 3

The SI unit of magnetic field intensity is

Answer 3

N / A-m

Question 4

The magnetic field produced at the centre of a circular coil carrying current is :

Answer 4

Perpendicular to the plane of coil

Question 5

The force on a charge moving in a uniform magnetic field is zero if the direction of motion of charge is :

Answer 5

parallel to the magnetic field

Question 6

In _____ device a high resistance is joined in series with the coil of galvanometer

Answer 6

Voltmeter

Question 7

A charged particle enters in a unifrom magnetic field parallel to field, the path of particle will be :

Answer 7

Straight line

Question 8

The SI unite of permeability and magnetic field is :

Answer 8

i) newton / ampere^2
ii) newton / (ampere x metre )

Question 9

Dimensional formula of magnetic field is :

Answer 9

M T^ -2 A ^ -1

Question 10

A current carrying solenoid behaves like a :

Answer 10

Bar magnet

Question 11

The lorence force on a charged particle in a uniform magnetic field is known as

Answer 11

q ( v x b)
;v & b are vectors

Question 12

The force between two parallel conductors carrying current in same direction is _______ in nature.

Answer 12

Attractive

Question 13

The resistance of an ideal voltmeter is _______

Answer 13

Infinite

Question 14

In an electric circuit, voltmeter is always joined in ________

Answer 14

parallel

Question 15

The resistance of an ideal ammeter is

Answer 15

Zero

Question 16

The force acting on a moving charge in a magnetic field is called

Answer 16

Lorentz force

Question 17

Magnetic field is a _____ quantity

Answer 17

Vector

Question 18

The ______ of the galvanometer is reduced by the use of shunt

Answer 18

Sensitivity

Question 19

What is the magnetic field at the centre of a current carrying pipe of copper

Answer 19

Zero

Question 20

What is the relation between radius of a current carrying coil and magnetic field produced at its centre

Answer 20

B is inversely proportional to R

Question 21

A charged particle enters in a uniform magnetic field parallel to field. What will be its path ?

Answer 21

The path of charged particle will be a straight line

Question 22

How is galvanometer converted into a voltmeter

Answer 22

To convert a galvanometer into voltmeter, a high resistance wire is joined in series with coil of galvanometer

Question 23

When will two parallel current carrying condecutors :
i) attract each other
ii) repel each other

Answer 23

i) when the current flows through parallel wires in same direction
ii) when the current flows through parallel wires in opposite direction

Question 24

SIGN CONVENTION OF CURRENT IN A FIELD

Answer 24

A current or a
field (electric or magnetic) emerging out of the plane of the paper is depicted by a dot (⨀). A current or a field going
into the plane of the paper is depicted by a cross (⨂ )

Question 25

FORCE DUE E AND B

Answer 25

F = q [ E (r) + v × B (r)] º F electric +F magnetic

Question 26

The magnetic force is zero if charge is not moving (as then |v|= 0). Only a moving charge feels the magnetic force.

Answer 26

true

Question 27

formula of b

Answer 27

[B] = [F/qv]

Question 28

Magnetic force on a current-carrying conductor

Answer 28

F = (nlA)q vd ´ B

Question 29

MOTION IN A MAGNETIC FIELD

Answer 29

The particle will describe a circle if v and B are perpendicular to each other motion in a plane perpendicular to B is as before a circular one, thereby producing a helical motion

Question 30

ANGLUAR FREQUWNCY of helical path

Answer 30

w = 2pi v = q B/ m

Question 31

time period of helical path

Answer 31

p = v||T = 2pm v||/ q B

Question 32

MAGNETIC FIELD DUE TO A CURRENT ELEMENT, BIOT-SAVART LAW

Answer 32

=µ0 I dl r/ 4π r^3

Question 33

µ0/4π=

Answer 33

10^-7 Tm/A

Question 34

DIFFERANCE BETWEEN E AND B

Answer 34

(i) Both are long range, since both depend inversely on the square of distance from the source to the point of interest. The principle of superposition applies to both fields. [In this connection, note that the magnetic field is linear in the source I dl just as the electrostatic field is linear in its source: the electric charge.] (ii) The electrostatic field is produced by a scalar source, namely, the electric charge. The magnetic field is produced by a vector source I dl. (iii) The electrostatic field is along the displacement vector joining the source and the field point. The magnetic field is perpendicular to the plane containing the displacement vector rand the current element I dl. (iv) There is an angle dependence in the Biot-Savart law which is not present in the electrostatic case. Along this line,q = 0, sin q = 0 and from|dB| = 0.

Question 35

ε0 µ0=

Answer 35

1/c^2

Question 36

MAGNETIC FIELD ON THE AXIS OF A CIRCULAR CURRENT LOOP

Answer 36

dB= µ0 I dl / 4 pi [x^2+R^2]

Question 37

WRITE RIGHT HAND THUMB LAW

Answer 37

Curl the palm of your right hand around the circular wire with the fingers pointing in the direction of the current. The right-hand thumb gives the direction of the magnetic field.

Question 38

AMPERE’S CIRCUITAL LAW

Answer 38

∮B.dl = µ0I

Question 39

MAGNETIC FIELD IN A LONG SOLENOID

Answer 39

B = µ0n I

Question 40

Parallel currents attract, and antiparallel currents repel

Answer 40

TRUE

Question 41

force b/w 2 parallel current carrying wire

Answer 41

fab = µ0 Ia Ib/ 2 pi d

Question 42

Torque on a rectangular current loop in a uniform magnetic field

Answer 42

ɽ= I A B A= area B= magnetic field

Question 43

magnetic moment of the current loop

Answer 43

m = I A

Question 44

Circular current loop as a magnetic dipole

Answer 44

refer ncert

Question 45

study moving coil galvonometer