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Guide to Physics IIT JEE

Ravi Raj Dudeja

Chapter 23

Magnetic Effects of Current - all with Video Answers

Educators

Chapter Questions

01:33

Problem 1

A $0.5 \mathrm{~m}$ long straight wire in which a current of $3.2 \mathrm{~A}$ is flowing is kept at right angle to a uniform magnetic field of $2.0 \mathrm{Tesla}$. The force acting on the wire will be
(a) $2 \mathrm{~N}$
(b) $2.4 \mathrm{~N}$
(c) $1.2 \mathrm{~N}$
(d) 3

Ajay Singhal
Ajay Singhal
Numerade Educator
01:03

Problem 2

The radius of each coil of a Helmholtz galvanometer is $0.1 \mathrm{~m}$ and number of tums in each is 25 . When a current is passed in it then the deflection of magnetic needle observed as $45^{\circ}$. If the horizontal component of earth's magnetic field is $0.314 \times 10^{-4}$ Tesla then the value of current will be
(a) $0.14 \mathrm{~A}$
(b) $0.28 \mathrm{~A}$
(c) $0.42 \mathrm{~A}$
(d) $0.07 \mathrm{~A}$

Narayan Hari
Narayan Hari
Numerade Educator
01:15

Problem 3

An electron is revolving in a circular path of radius $2.0 \times 10^{-10} \mathrm{~m}$ with a uniform speed of $3 \times 10^{-5} \mathrm{~m} / \mathrm{s}$. The magnetic induction at the centre of the circular path will be
(a) 0.6 Tesla
(b) 1.2 Tesla
(c) 0.12 Tesla
(d) zero

Ajay Singhal
Ajay Singhal
Numerade Educator
01:56

Problem 4

Two parallel straight conductors, in which current is flowing in the same direction, attract each other. The cause of it is
(a) magnetic force between the two
(b) electric force between the two
(c) potential difference between the two
(d) mutual induction between the two

Vishal Gupta
Vishal Gupta
Numerade Educator
01:01

Problem 5

A rectangular loop, carrying current $i$, is lying near a long straight conductor $P Q$ as shown in the figure in such away that the wire is parallel to one of the sides of the loop and is in the plane of the loop. If constant current $I$ is passed in the wire then the loop will
(Figure can't copy)
(a) move towards the wire
(b) move away from the wire
(c) remain stationary
(d) rotate about an axis parallel to the wire

Narayan Hari
Narayan Hari
Numerade Educator
01:16

Problem 6

The distance between two thin long straight parallel conducing wires is $b$. On passing the same current $i$ in them, the force per unit length between them will be
(a) $\frac{\mu_0 i}{2 \pi b}$
(b) $\frac{\mu_0 i^2}{2 \pi}$
(c) $\frac{\mu_i i^2}{2 \pi b}$
(d) zero

Ajay Singhal
Ajay Singhal
Numerade Educator
01:27

Problem 7

The wall of a straight tube of infinite length is thin. On passing current $i$ through it, the value of magnetic induction inside the tube will be
(a) $\frac{2 i}{r}$
(b) $\frac{2 i \mu_0}{r}$
(c) $\frac{2 r}{i}$
(d) Zero

Ankur S
Ankur S
Numerade Educator
01:14

Problem 8

A proton and an electron, with same momenta, enter a magnetic field in a direction at right angles to the lines of force. If the radii of their circular paths arc $r p$ and $r$ respectively then the value of $\mathrm{rp}$ :re will be
(a) $1: 1$
(b) $1: 2$
(c) $2: 1$
(d) $4: 1$

Narayan Hari
Narayan Hari
Numerade Educator
01:01

Problem 9

A magnetic needle placed in a non-uniform magnetic field experiences
(a) only force
(b) force and torque
(c) only torque
(d) neither force nor torque

Narayan Hari
Narayan Hari
Numerade Educator
01:01

Problem 10

A current $i$ is flowing in a specific wire. It is tumed into a circular coil of one turn. Then it is turned to make a coil of two turns and smaller radius. Now the magnetic induction at the centre for same current will be
(a) half of its previous value
(b) one fourth of its previous value
(c) four times of its previous value
(d) zero

Narayan Hari
Narayan Hari
Numerade Educator
03:30

Problem 11

Uniform electric and magnetic fields are directed along $X$-direction. An electron is projected in $X$-direction with a velocity $v$, then
(a) magnitude of velocity of electron will increase
(b) magnitude of velocity of electron will decrease
(c) electron will turn towards right
(d) electron will turn towards left

Aja S
Aja S
Numerade Educator
01:18

Problem 12

The force between two parallel conductors, each of length $50 \mathrm{~m}$ and distant $20 \mathrm{~cm}$ apart, is 1 newton. If the current in one conductor is double that in another one, then their values will respectively be
(a) $100 \mathrm{~A}$ and $200 \mathrm{~A}$
(b) $50 \mathrm{~A}$ and $400 \mathrm{~A}$
(c) $10 \mathrm{~A}$ and $30 \mathrm{~A}$
(d) $5 \mathrm{~A}$ and $25 \mathrm{~A}$

Ankur S
Ankur S
Numerade Educator
01:27

Problem 13

The magnetic induction due to a straight currentcarrying conductor of infinite length at a distance $d$ from it will be
(a) $\frac{\mu_0 i}{2 d}$
(b) $\frac{\mu_0 i}{2 \pi d}$
(c) zero
(d) $\frac{\mu_0 i}{4 \pi d}$

Ankur S
Ankur S
Numerade Educator
01:08

Problem 14

On applying a uniform magnetic field on a currentcarrying coil the coil rotates in such a way that its plane
(a) becomes perpendicular to magnetic field
(b) becomes parallel to magnetic field
(c) makes an angle of $45^{\circ}$ with the magnetic field
(d) makes any angle with the magnetic field

Raj Bala
Raj Bala
Numerade Educator
00:30

Problem 15

Which of the following quantities is not affected by a magnetic field?
(a) Stationary charge
(b) Moving charge
(c) Change in magnetic flux
(d) Current flowing in a conductor

Paul Gabriel
Paul Gabriel
Numerade Educator
01:16

Problem 16

The magnetic field inside a solenoid is
(a) infinite
(b) zero
(c) uniform
(d) non-uniform

Hunza Gilgit
Hunza Gilgit
Numerade Educator
02:16

Problem 17

A current of $10 \mathrm{~A}$ is flowing in a wire of length $1.5 \mathrm{~m}$. When it is placed in a uniform magnetic field of 2 Tesla then a force of $15 \mathrm{~N}$ acts on it. The angle between the magnetic field and the direction of current flow will be
(a) $30^{\circ}$
(b) $45^{\circ}$
(c) $60^{\circ}$
(d) $90^{\circ}$

Joseph Petrullo
Joseph Petrullo
Numerade Educator
03:32

Problem 18

A wire is lying parallel to a square coil. Same current is flowing in same direction in both of them. The magnetic induction at any point $P$ inside the coil will be
(Figure can't copy)
(a) zero
(b) more than that produced by only coil
(c) less than that produced by only coil
(d) equal to that produced by only coil.

Saman Zulfiqar
Saman Zulfiqar
Numerade Educator
02:58

Problem 19

If the currents in two straight current-carrying conductors, disatant $d$ apart, are $i_1$ and $i_2$ respectively in the same direction then they will
(Figure can't copy)
(a) rotate about a central axis
(b) attract each other
(c) repel each other
(d) neither attract nor repel each other

Supratim Pal
Supratim Pal
Numerade Educator
01:21

Problem 20

The correct curve between the magnetic induction $(B)$ along the axis of a long solenoid due to current flow i in it and distance $x$ from one end is
(Figure can't copy)

Varsha Aggarwal
Varsha Aggarwal
Numerade Educator
01:02

Problem 21

Gauss is the unit of
(a) $B$
(b) $H$
(c) $M$
(d) 1

Narayan Hari
Narayan Hari
Numerade Educator
02:46

Problem 22

The correct expression for Lorent force is
(a) $q[\vec{E}+(\vec{B} \times \vec{V})]$
(b) $q[\vec{E}+(\vec{V} \times \vec{B})]$
(c) $q(\vec{V} \times \vec{B})$
(d) $q \vec{E}$

Prem Bijarniya
Prem Bijarniya
Numerade Educator
01:07

Problem 23

The correct relation between $B$ and $M$ for a small current-carrying coil is
(a) $B=\frac{\mu_0 M}{2 x^3}$
(b) $B=\frac{\mu_0 M}{x^3}$
(c) $B=\frac{\mu_0 M}{\pi x^3}$
(d) $B=\frac{\mu_0 M}{2 \pi x^3}$

Hast Aggarwal
Hast Aggarwal
Numerade Educator
01:22

Problem 24

A proton, a deutron and an $a$-particle are moving with same momentum in a uniform magnetic field. The ratio of magnetic forces acting on them will be
(a) $1: 1: 2$
(b) $1: 2: 3$
(c) $2: 1: 1$
(d) $1: 1: 1$

Ankur S
Ankur S
Numerade Educator
01:22

Problem 25

An $a$-particle, a deutron and a proton are moving with same momentum in a uniform magnetic field. The ratio of their speeds will be
(a) $1: 2: 4$
(b) $4: 2: 1$
(c) $1: 1: 1$
(d) $2: 2: 4$

Ankur S
Ankur S
Numerade Educator
00:15

Problem 26

The value of $B$, at the point of inflexion in $B$-x curve is
(a) maximum
(b) positive
(c) constant
(d) negative

Fuzail Shakir
Fuzail Shakir
Numerade Educator
03:01

Problem 27

The resultant force on the current loop $P Q R S$ due to a long current-carrying conductor will be, if the current flow in the loop is clockwise,
(Figure can't copy)
(a) zero
(b) $0.36 \times 10^{-3} \mathrm{~N}$
(c) $1.8 \times 10^{-3} \mathrm{~N}$
(d) $0.5 \times 10^{-3} \mathrm{~N}$

Supratim Pal
Supratim Pal
Numerade Educator
02:36

Problem 28

A small linear segment of an electric circuit is lying on $x$-axis extending from $x=-a / 2$ to $x=a / 2$ and a current $t$ is flowing in it. The magnetic induction due to the segment at a point $x=a$ will be
(a) $\propto a$
(b) Zero
(c) $\propto a^2$
(d) $\alpha \frac{1}{a}$

Saman Zulfiqar
Saman Zulfiqar
Numerade Educator
01:01

Problem 29

The rays, which remain undeflected in a magnetic field, are
(a) $\propto$-rays
(b) $\boldsymbol{\beta}$-rays
(c) $\gamma$ rays
(d) positive rays.

Narayan Hari
Narayan Hari
Numerade Educator
02:32

Problem 30

A current $\mathrm{i}$ is flowing in a straight conductor of length L. The magnetic induction at a point distant from its centre will be
(a) $\frac{4 \mu_0 i}{\sqrt{5} \pi L}$
(b) $\frac{\mu_0 i}{\sqrt{2} L}$
(c) $\frac{\mu_0 t}{2 \pi L}$
(d) zero

Supratim Pal
Supratim Pal
Numerade Educator
00:40

Problem 31

A current-carrying circular coil of magnetic moment $M$ is situated in a magnetic field $B$. The work done in deflecting it from an angle $0^\beta$ to $\theta^{\circ}$ will be
(a) $M B$
(b) $M B(1-\cos \theta)$
(c) $-M B$
(d) $M B(1-\sin \theta)$

Hast Aggarwal
Hast Aggarwal
Numerade Educator
01:33

Problem 32

Same current $i$ is flowing in two straight parallel conducting wires situated a distance $d$ apart. The magnetic induction at the centre between two wires will be
(a) zero
(b) $\frac{\mu_0 d}{d}$
(c) $\frac{4 \mu_0 i}{d}$
(d) $\frac{\mu_0 f}{2 d}$

Narayan Hari
Narayan Hari
Numerade Educator
01:49

Problem 33

A uniform magnetic field $B$ and a uniform electric field $E$ act in a common region. An electron is entering this region of space. The correct arrangement for it to escape undeviated is
(Figure can't copy)

Anand Jangid
Anand Jangid
Numerade Educator
01:23

Problem 34

A current of 30 amp is flowing in a conductor as shown in the figure. The magnetic induction at point $O$ will be
(Figure can't copy)
(a) 1.5 Tesla
(b) $4.71 \times 10^{-4} \mathrm{Tesla}$
(c) zero
(d) 0.15 Tesla

Narayan Hari
Narayan Hari
Numerade Educator
01:02

Problem 35

A current is flowing in a hexagonal coil of side $a$. The magnetic induction at the centre of the coil will be
(Figure can't copy)
(a) $\frac{3 \sqrt{3} \mu_0}{\pi a}$
(b) $\frac{\mu_0 i}{3 \sqrt{3} \pi a}$
(c) $\frac{\mu_0 i}{\sqrt{3} \pi a}$
(d) $\frac{\sqrt{3} \mu_0 t}{\pi a}$

Narayan Hari
Narayan Hari
Numerade Educator
01:02

Problem 36

A current $i$ is flowing in an octagonal coil of side $a$. The magnetic induction at the centre of the coil will be
(Figure can't copy)
(a) $\frac{5 \mu_j}{4 \pi a}$
(b) $\frac{5 \sqrt{2} \mu_0 i}{\pi a}$
(c) $\frac{\mu_0 i}{\sqrt{5} \pi a}$
(d) $\frac{\sqrt{5} \mu_o i}{2 \pi a}$

Narayan Hari
Narayan Hari
Numerade Educator
03:06

Problem 37

Two similar coils of radius $R$ and number of turns $N$ are lying concentrically with their planes at right angles to each other. The currents flowing in them are $I$ and $I \sqrt{3}$ respectively. Then the resultant magnetic induction at the centre will be (in $\mathrm{Wb} / \mathrm{m}^2$ ).
(a) $\frac{\mu_0 N I}{2 R}$
(b) $\frac{\mu_0 N I}{R}$
(c) $\sqrt{3} \mu_0 \frac{N I}{2 R}$
(d) $\sqrt{5} \frac{\mu_0 N I}{2 R}$

Aja S
Aja S
Numerade Educator
01:31

Problem 38

A current of $10^{-3} \mathrm{~A}$ is flowing in aresistance of $1000 \Omega$. To measure potential difference accurately, a voltmeter should be used whose resistance is
(a) $0 \Omega$
(b) $500 \Omega$
(c) $1000 \Omega$
(d) $\gg 1000 \Omega$

Varsha Aggarwal
Varsha Aggarwal
Numerade Educator
02:09

Problem 39

A galvanometer with resistance $100 \Omega$ gives full scale deflection with a current of $10 \mathrm{~m} A$. The value of shunt, in order to convert it into an ammeter of 10 ampere range, will be
(a) $-10 \Omega$
(b) $1 \Omega$
(c) $0.1 \Omega$
(d) $0.01 \Omega$

Mahipal Kumawat
Mahipal Kumawat
Numerade Educator
02:00

Problem 40

An ammeter gives full scale deflection with a current of 1 amp. It is converted into an ammeter of range 10 amp. The ratio of the resistance of ammeter to the shunt resistance used will be
(a) $1: 9$
(b) $1: 10$
(c) $1: 11$
(d) $9: 1$

Supratim Pal
Supratim Pal
Numerade Educator
02:17

Problem 41

The value of shunt resistance, in order to pass $10 \%$ of the main current in the galvanometer of resistance 99 $\Omega$, will be
(a) $9.9 \Omega$
(b) $10 \Omega$
(c) $11 \Omega$
(d) $9 \Omega$

Mahipal Kumawat
Mahipal Kumawat
Numerade Educator
01:01

Problem 42

A galvanomenter with resistance $5 \Omega$ can read upto 5 $\mathrm{m} A$. If this instrument is to be used to read upto 100 volt, then the value of resistance to be used in its series will be
(a) $19.9995 \Omega$
(b) $199.995 \Omega$
(c) $1999.95 \Omega$
(d) $19995 \Omega$

Narayan Hari
Narayan Hari
Numerade Educator
01:29

Problem 43

An ammeter of resistance $0.2 \Omega$ and range $10 \mathrm{~m} A$ is to be used to read potential difference upto I volt. It will have to be connected to
(a) $99.8 \mathrm{~W}$ resistance in series
(b) $99.8 \mathrm{~W}$ resistance in parallel
(c) $0.1 \mathrm{~W}$ resistance in parallel
(d) $0.1 \mathrm{~W}$ resistance in series

Saman Zulfiqar
Saman Zulfiqar
Numerade Educator
01:01

Problem 44

The proper resistance to be connected in series with a voltmeter, in order to increase its range 10 times, will be
(a) nine times the resistance of voltmeter
(b) ten times the resistance of voltmeter
(c) eleven times the resistance of voltmeter
(d) one-tenth the resistance of voltmeter

Narayan Hari
Narayan Hari
Numerade Educator
01:01

Problem 45

The resistance required to be connected in parallel to an ammeter in order to increase its range 10 times, will be
(a) one-tenth the resistance of ammeter
(b) nine times the resistance of ammeter
(c) ten times the resistance of ammeter
(d) one-ninth the resistance of ammeter

Narayan Hari
Narayan Hari
Numerade Educator
01:01

Problem 46

A galvanometer of resistance $501 \mathrm{~W}$ gives full scale deflection with a current of $0.5 \mathrm{~m} A$. The value of resistance to be connected in series with it, in order to convert it into a voltmeter of range 10 volt, will be
(a) $1,995 \Omega$
(b) $2,000 \Omega$
(c) $19,950 \Omega$
(d) $20,000 \Omega$

Narayan Hari
Narayan Hari
Numerade Educator
02:17

Problem 47

If only $1 \%$ of main current is to be passed through a galvanometer of resistance $G$, then the value of shunt resistance will be
(a) $\frac{G}{50}$
(b) $\frac{G}{49}$
(c) $\frac{G}{99}$
(d) $99 G$

Mahipal Kumawat
Mahipal Kumawat
Numerade Educator
01:06

Problem 48

A current of $10^{-7}$ ampere produces 50 division deflection in a galvanometer. Then its figure of merit will be
(a) $10^{-4}$ amp/div
(b) $10^{-8}$ amp/div
(c) $10^{-10}$ amp/div
(d) $2 \times 10^{-9} \mathrm{amp} / \mathrm{div}$

Narayan Hari
Narayan Hari
Numerade Educator
01:14

Problem 49

A voltmeter of $1000 \Omega$ can read potential difference of 1.5 volt. What resistance will have to be connected in series with it, in order to measure potential difference upto 6 volt with the help of this voltmeter?
(a) $3000 \Omega$
(b) $500 \Omega$
(c) $1,000 \Omega$
(d) $10,000 \Omega$

Varsha Aggarwal
Varsha Aggarwal
Numerade Educator
01:06

Problem 50

The figures of merit of two galvanometers, whose resistances are $100 \Omega$ and $20 \Omega$ respectively, are $1^{\prime} 10^{-8} \mathrm{amp} /$ div and $2{ }^{\prime} 10^{-9} \mathrm{amp} /$ div respectively. The galvanometer, whose voltage sensitivity is more, is
(a) nothing can be predicted
(b) second
(c) both
(d) first.

Narayan Hari
Narayan Hari
Numerade Educator
01:06

Problem 51

A resistance of $900 \Omega$ is connected in series with a galvanometer of resistance $100 \Omega$. A potential difference of 1 volt produces 300 division deflection in the galvanometer. The value of figure of merit will be
(a) $10^{-2} \mathrm{~A} / \mathrm{div}$
(b) $10^{-3} \mathrm{~A} / \mathrm{div}$
(c) $10^{-4} \mathrm{~A} / \mathrm{div}$
(d) $10^{-5} \mathrm{~A} / \mathrm{div}$

Narayan Hari
Narayan Hari
Numerade Educator
02:13

Problem 52

A proton, a deutron and an $\alpha$-particle are accelerated through the same potential difference and then they enter a uniform normal magnetic field. If the radius of circular path of proton is $8 \mathrm{~cm}$ then the radius of circular path of deutron will be
(a) $11.31 \mathrm{~cm}$
(b) $22 \mathrm{~cm}$
(c) $5 \mathrm{~cm}$
(d) $2.5 \mathrm{~cm}$

Narayan Hari
Narayan Hari
Numerade Educator
01:12

Problem 53

A proton and an $\alpha$-particle enter a uniform magnetic field at right angles to it with same velocity. The time period of $\alpha$ particle as compared to that of proton, will be
(a) four times
(b) two times
(c) half
(d) one-fourth

Ankur S
Ankur S
Numerade Educator
01:14

Problem 54

A charged particle with charge $q$ is moving in a uniform magnetic field. If this particle makes any angle with the magnetic field then its path will be
(a) circular
(b) straight line
(c) helical
(d) parabolic

Narayan Hari
Narayan Hari
Numerade Educator
13:08

Problem 55

A proton is moving with a velocity of $3 \times 10^7 \mathrm{~m} / \mathrm{s}$ in the direction of a uniform magnetic field of 0.5 Tesla. The force acting on proton is
(a) $2 \mathrm{~N}$
(b) $4 \mathrm{~N}$
(c) $6 \mathrm{~N}$
(d) zero

Daniel Azubuike
Daniel Azubuike
Numerade Educator
01:02

Problem 56

The work done by a normal magnetic field in revolving a charged particle $q$ in a circular path will be
(a) zero
(b) $M B(1-\cos \theta)$
(c) $M B$
(d) $-M B$

Narayan Hari
Narayan Hari
Numerade Educator
10:49

Problem 57

An electron is moving vertically downwards at any place. The direction of magnetic force acting on it due to horizontal component of earth's magnetic field will be
(a) towards east
(b) towards west
(c) towards north
(d) towards south

Ryan Eaton
Ryan Eaton
Numerade Educator
01:39

Problem 59

Two parallel wires $P$ and $Q$ carry electric currents of 10 $A$ and $2 A$ respectively in mutually opposite directions. The distance between the wires is $10 \mathrm{~cm}$. If the wire $P$ is of infinite length and wire $Q$ is $2 \mathrm{~m}$ long, then the force acting $Q$ will be
(a) $4 \times 10^{-5} \mathrm{~N}$
(b) $8 \times 10^{-5} \mathrm{~N}$
(c) $4 \times 10^5 \mathrm{~N}$
(d) $0 \mathrm{~N}$

Ajay Singhal
Ajay Singhal
Numerade Educator
01:04

Problem 60

A proton with kinetic energy $8 \mathrm{el}$ ' is moving in a uniform magnetic field. The kinetic energy of a deutron moving in the same path in the same magnetic field will be
(a) $2 \mathrm{eV}^{\circ}$
(b) $4 \mathrm{eV}^{-}$
(c) $6 \mathrm{el}^{\prime}$
(d) $8 \mathrm{el}^{\mathrm{V}}$

Narayan Hari
Narayan Hari
Numerade Educator
01:01

Problem 61

Two wires carry currents of $100 \mathrm{~A}$ and $200 \mathrm{~A}$ respectively and they repel each other with a force of $0.4 \mathrm{~N} / \mathrm{m}$. The distance between them will be
(a) $1 \mathrm{~m}$
(b) $1 \mathrm{~cm}$
(c) $50 \mathrm{~cm}$
(d) $25 \mathrm{~cm}$

Narayan Hari
Narayan Hari
Numerade Educator
01:02

Problem 62

A current of $2 A$ is flowing in a wire of length $50 \mathrm{~cm}$. If this wire is lying in a uniform magnetic field of $5 \times 10^{-4}$ N/A $-\mathrm{m}$ making an angle of $60^{\circ}$ with the field, then the force acting on the wire will be
(a) $4.33 \times 10^{-4} \mathrm{~N}$
(b) $4 \mathrm{~N}$
(c) 4 dyne
(d) Zero

Ajay Singhal
Ajay Singhal
Numerade Educator
01:19

Problem 63

In the following figure, three paths of a particle crossing a nucleus $N$ are shown. The correct path is
(Figure can't copy)
(a) a and c
(b) a and b
(c) a, b, and c
(d) only a

Ajay Singhal
Ajay Singhal
Numerade Educator
02:38

Problem 64

The ratio of magnetic force $(F m)$ and electric force $(F e)$ acting on a moving charge is
(a) $\left(\frac{V^{\prime}}{C}\right)^2$
(b) $\left(\frac{C}{V}\right)^2$
(c) $\frac{V}{C}$
(d) $\frac{C}{V}$

Vysakh M
Vysakh M
Numerade Educator
02:53

Problem 65

A charge of 0.04 coulomb is moving in a magnetic field of 0.02 Tesla with a velocity $10 \mathrm{~m} / \mathrm{s}$ in a direction making an angle $30^{\circ}$ with the direction of field. The force acting on it will be
(a) $4 \times 10^{-3} \mathrm{~N}$
(b) $2 \times 10^{-3} \mathrm{~N}$
(c) zero
(d) $8 \times 10^{-3} \mathrm{~N}$

Jarrad Pond
Jarrad Pond
Numerade Educator
01:03

Problem 66

An electron is moving in a perpendicular magnetic field of strength $4 \times 10^{-3}$ Tesla with a velocity of $4 \times 10^7$ $\mathrm{m} / \mathrm{s}$. The radius of electron path will be
(a) $0.056 \mathrm{~m}$
(b) $0.056 \mathrm{~m}$
(c) $56 \mathrm{~m}$
(d) $5.6 \mathrm{~m}$

Narayan Hari
Narayan Hari
Numerade Educator
01:53

Problem 67

The magnetic moment of an electron with orbital angular momentum $J$ will be
(a) $\frac{e \vec{J}}{m}$
(b) $\frac{e \vec{J}}{2 m}$
(c) $\frac{2 m}{e \bar{J}}$
(d) zero

Mahendra K
Mahendra K
Numerade Educator
01:37

Problem 68

The correct statement about magnetic moment is:
(a) It is a vector quantity.
(b) Its unit is amp- $\mathrm{m}^2$.
(c) Its dimensions are $\mathrm{AL}^2$
(d) All of the above.

Ajay Singhal
Ajay Singhal
Numerade Educator
01:01

Problem 69

The use of Helmholtz coils is to produce
(a) uniform magnetic field
(b) non-uniform magnetic field
(c) varying magnetic field
(d) zero magnetic field

Narayan Hari
Narayan Hari
Numerade Educator
01:02

Problem 70

The magnetic induction due to a straight currentcarrying conductor of infinite length at a distance $r$ from it proportional to
(a) $i^{-1}$
(b) $i$
(c) $i^{-2}$
(d) $i^2$

Narayan Hari
Narayan Hari
Numerade Educator
01:42

Problem 71

If a load is suspended from a spring and a direct current is passed through it then the spring gets
(a) stretched
(b) compressed
(c) sometimes stretched and sometimes compressed
(d) neither stretched nor compressed

Kamlesh Goyal
Kamlesh Goyal
Numerade Educator
01:07

Problem 72

The correct expression for Ampere's law is
(a) $\oint B \cdot d l=\Sigma i$
(b) $\oint B \cdot d l=\frac{1}{\Sigma i}$
(c) $\oint B \cdot d l=\mu_0 \Sigma i$
(d) $\oint B d l=\frac{\Sigma i}{\mu_0}$

Ajay Singhal
Ajay Singhal
Numerade Educator
00:56

Problem 73

The magnitude of magnetic induction for a currentcarrying toroid of uniform cross-section is
(a) uniform over the whole cross-section
(b) maximum on the outer edge
(c) maximum on the inner edge
(d) maximum at the centre of cross-section

Hast Aggarwal
Hast Aggarwal
Numerade Educator
01:25

Problem 74

If a positively charged particle is moving as shown in the figure, then it will get deflected due to magnetic field towards
(Figure can't copy)
(a) $+x$ direction
(b) $+y$ direction
(b) $-x$ direction
(d) $+z$ direction

Ajay Singhal
Ajay Singhal
Numerade Educator
01:08

Problem 75

A current-carrying loop lying in a magnetic field behaves like a
(a) magnetic dipole
(b) magnetic pole
(b) magnetic material
(d) non-magnetic material

Hast Aggarwal
Hast Aggarwal
Numerade Educator
01:02

Problem 76

The ratio of magnetic induction due to a bar magnet on its axial point and equatorial point will be
(a) $1: 1$
(b) $1: 2$
(c) $2: 1$
(d) $1: 4$

Narayan Hari
Narayan Hari
Numerade Educator
01:24

Problem 77

Two insulated wires of infinite length are lying mutually at right angles to each other as shown in the figure. Current of $2 \mathrm{~A}$ and $1.5 \mathrm{~A}$ respectively are flowing in them. The value of magnetic induction at point $P$ will be
(Figure can't copy)
(a) $2 \times 10^{-3} \mathrm{~N} / \mathrm{A}-\mathrm{m}$
(b) $2 \times 10^{-5} \mathrm{~N} / \mathrm{A}-\mathrm{m}$
(c) Zero
(d) $2 \times 10^{-4} \mathrm{~N} / \mathrm{A}-\mathrm{m}$

Varsha Aggarwal
Varsha Aggarwal
Numerade Educator
01:18

Problem 78

Two current-carrying parallel conductors are shown in the figure. The magnitude and nature of force acting between them per unit length will be
(Figure can't copy)
(a) $8 \times 10^{-8} \mathrm{~N} / \mathrm{m}$, attractive
(b) $3.2 \times 10^{-5} \mathrm{~N} / \mathrm{m}$, repulsive
(c) $3.2 \times 10^{-5} \mathrm{~N} / \mathrm{m}$, attractive
(d) $8 \times 10^{-8} \mathrm{~N} / \mathrm{m}$, repulsive

Ankur S
Ankur S
Numerade Educator