Magnetic Field Questions and Answers

9 Magnetic field in a region is given by B Bi Boj Torque on a circular loop x2 z2 r carrying current i in anticlockwise direction as seen from a point on positive Y axis is 1 inr k 3 inr Bk 2 inrBok 4 inr Bok

The density of turns of a very long solenoid of diameter 1 cm is 2000 m The strength of the magnetic field produced by the coil at a distance of 5 cm from the axis of the solenoid is 4 x 104 T Determine the strength of the magnetic field inside the solenoid A 0 125 T C 0 502 T B 0 251 T D 0 351 T O

A magnetic field B Boj exists in the region a x 2a and B Boj in the region 2a x 3a where B is a positive constant A positive point charge moving with a velocity v voi where vo is a positive constant enters the magnetic field at x a The trajectory of the charge in this region can 2007 3M be like

2 A uniform magnetic field B exists in the region between x 0 and x figure pointing normally into the plane of the paper A particle with charge Q and momentum p directed along x axis enters region 2 from region 1 at point P y R Which of the following option s is are correct Region 1 A Region 2 B For B O Q P y R X X X X X X X X X B X X X X 3R 2 A For B the particle will re enter region 1 3 QR Region 3 P 8 p 13 QR the particle will enter region 3 through the point P on x axis C When the particle re enters region 1 through the longest possible path in region 2 the magnitude of the change in its linear momentum between point P and the farthest point from y axis is p 2 D For a fixed B particles of same charge Q and same velocity v the distance between the point P and the point of re entry into region 1 is inyersely prono mass of the partial

An equilateral triangular loop PQR of side a is at the edge of a uniform magnetic field B at t 0 as shown in the figure a It is pulled to the right with a constant velocity v and its edge R leaves the region of magnetic field at t to Which of the graphs shown in figure b represents the variation of induced current i with time t A 1 C to B D to t X x R X X X X X X X X X X X X X X X Q B

A uniform conducting wire of length 30a and resistance of R is wound up as current carrying coil in shape of regular hexagon of sides a If coil is connected to a voltage source V then magnetic moment of coil is a a 1 3 3 3va 2R 15 3Va 2R 2 4 a 5 3Va R 7 3Va R

5 Force per unit length between parallel wires in the circuit is 3 6x10 N m Resistance of the circuit is 18V T OT 1 3Q 1 2m 8mm 2 1 50 www ER 3 4 50 4 69

Column I Column II a Torque b Angular momentum c Linear Velocity d Couple acting on a bar magnet p C MxB q V Wxr r T rxF s Z rxP

77 There is a solenoid of length 1 5 m having 1000 tums per metre kept in a region where magnet field is increased with time as 0 2 T s radius of 10 solenoid is cm The current through resistance 10 is 1 30 A 3 0 3 A A B To B www R 10 Q B 2 3 A 4 0 03 A

Q 24 The density of turns of a very long solenoid of diameter 1 cm is 2000 m The strength of the magnetic field produced by the coil at a distance of 5 cm from the axis of the solenoid is 4 x 10 T Determine the strength of the magnetic field inside the solenoid A 0 125 T B 0 251 T O 5 cm P C 0 502 T D 0 351 T

The magnetic field due to a current carrying circular loop of radius 3 cm at a point on the axis at a distance of 4 cm from the centre is 54 T What will be its value at the centre of the loop a 250 T c 125 T b d 150 T 75 T

3 A negative charge is coming towards the observer The direction of the magnetic field produced by i will be as seen by observer 1 Clockwise 2 Anti clockwise 3 In the direction of motion of charge In the direction opposite to the mu cho

Figure shows an amperian path ABCDA Part ABC is in vertical plane PSTU while part CDA is in horizontal plane PQRS Direction of circulation along the path is shown by an arrow near point B and at D fBd7 for this path according to Ampere s law will be C 5 13 40 P 10 10 13 13 N 1 1 13 0 B S D 0 20 R

For the situation shown in figure find the force experienced by side MN of the rectangular loop M 5 Vr

5 A wire along x axis carries a current 3 5 A Find the force on a 1 cm section of the wire exerted by B 0 74 TJ 0 3 Tk a 2 59k 1 26 x 10 b 1 26k 2 59 10 c 2 59k 1 267 10 d 1 26 2 597 10

7 What will be the direction of current in the coil A as the switch S is closed B A 1 Clockwise 2 Anticlockwise 3 Anticlockwise and then clockwise Jarno S

3 If a proton enters perpendicularly a magnetic field with velocity v then time period of revolution is T If proton enters with velocity 2v then time period will be 1 T 3 3T 2 2T 4 4T

16 Two long wires carrying current are kept crossed not joined at O The locus where magnetic field is zero is a 4 1 y c I I I 0 12 b 4 1 d I 1

3 In the figure 0 tan 2 then the correct direction of the magnetic field at P can be shown by the arrow No S 1 2 3 2K 2 4 4 3

Two coils are at fixed locations When coil 1 has no current and the current in coil 2 increases at the rate 15 0 A s the emf in coil 1 in 25 0 mV when coil 2 has no current and coil 1 has a current of 3 6 A the flux linkage in coil 2 is 1 16 mWb 3 4 00 mWb 2 10 mWb 4 6 00 mWb

9 4 1 2 N Two identical bar magnets each of magnetic moment M are placed as shown in figure Magnetic field at point Pis 1 2 3 Mo M 4 d 5 Ho M 4 d N P 2 d N Mo M 4 d 4 2 5 Mo M 4 d

Find the equivalent resistance between the terminals of A and B in the network shown in the figure below given that the resistance of each resistor is 10 ohm C www 1 1 www 1 1 www 1 1 H

A circular loop of flexible conducting material is kept in a magnetic field directed perpendicularly into its plane By holding the loop at diametrically opposite points its is suddenly stretched outwards then 1 No current is induced in the loop 2 Anti clockwise current is induced 3 Clockwise current is induced 4 Only emf is indund

COMPREHENSIC A positively charged particle having specific charge q m is projected at t 0 from origin in a gravity free space An uniform constant electric field E exists in space Initial velocity of the particle is v at an angle of 60 with the x 3mv a uniform magnetic field axis in x y plane as shown in the figure At t 2qE B B is also switched on in the space Answer the following question based on the above passage 4 What is the maximum positive z coordinate of the particle during its motion mv A B 2qBo 2mv qBo C mv qBo D Zero E 60 Bo Jik

12 A 2 0 m wire segment carrying a current of 0 60 A oriented parallel to a uniform magnetic field of 0 50 T experiences a force of what magnitude 0 60 N 0 15 N 0 30 N 0 0 N

When we Change to the system cause turn the magnet and the coil so that the stickers are facing in When we turn the coil around so that the magnet sticker is facing in and the coil sticker is facing out When we turn the magnet around so that the magnet sticker is facing out and the coil sticker is facing in we will observe we will observe we will observe The effect on the system because because because Draw a picture of the fore on the magnet and the ca O O I

en e Change to the system cause turn the magnet around so that the magnet sticker is facing out and the we will observe The effect on the syst

Which of the following showed evidence that electricity and magnetism were connected a floating piece of magnetite aligns with the magnetic field of a magnet the Earth acts as a large bar magnet causing magnetic fields an iron nail brought close to a magnet causes the nail to be magnetic the needle of a compass is deflected if brought close to a wire

25 What defines whether or not an object is magnetic O The atoms are all neutrally charged The atoms have large electron affinity The atoms are aligned in the same direction The atoms are randomly aligned

10 Faraday s Law states O Moving magnetic fields can induce an electric field voltage O Electric fields and magnetic fields are not related Electromagnetic forces are a product of particle charge and sp Stationary charges create magnetic fields

17 An electron moving south through a magnetic field pointing toward the west experiences a force tha Oto the west to the north out of the page into the page

hen ve Change to the system cause turn the coil around so that the magnet sticker is facing in and the coil sticker is we will observe The effect on the sys

14 The lines of the magnetic field around a current carrying wire x point away from the wire form circles around the wire are parallel with the wire point toward the wire

9 The purpose of the Seller Financing Addendum and Buyer Financial Information Sheet is to O a have the buyer agree to read the due diligence document O b have the seller disclose all material information regarding the property O c verify that documents have been delivered to the parties in the transaction d have the buyer disclose his or her finances to the seller in the event of seller financing

Problem 2 A mass spectrometer is constructed as shown It is used for determining the mass of singly ionized positively charged ions missing 1 electron There is a uniform magnetic field B 0 20 tesla is perpendicular to the page within the shaded region inside the whole box A potential difference of V 1500 V is applied across the parallel plates L and K which are separated by a distance d 0 012 meter and which act as a velocity selector see problem 19 6 in book a 3 points In which direction relative to the coordinate system shown should the magnetic field point in order for positive ions to move along the path shown by the dashed line in the diagram Explain V 1 500 V d 0 012 m Region of Magnetic Field B X Positive z out of page b 3 points Should plate K have a positive or negative polarity relative to plate L Explain c 6 points Calculate the magnitude of the electric filed between the plates d 7 points Calculate the speed of a particle that can pass between the parallel plates without being deflected e 6 points Calculate the mass of the singly charged ion that travels in a semicircle of radius R 0 50 meter

A mass spectrometer is being used to separate common oxygen 16 from the much rarer oxygen 18 taken from a sample of old glacial ice The relative abundance of these oxygen isotopes is related to climatic temperature at the time the ice was deposited The ratio of the masses of these two ions is 16 to 18 the mass of oxygen 16 is 2 66 x 10 26 kg and they are singly charged and travel at 6 70 x 106 m s in a 1 30 T magnetic field What is the separation in m between their paths when they hit a target after traversing a semicircle m

50 A wire 0 89 m long experiences a magnetic force of 1 3 N due to a perpendicular uniform magnetic field If the wire carries a current of 12 0 A what is the magnitude of the magnetic field

The angular velocity of a process control motor is 24 rad s where t is in seconds Part A At what time does the motor reverse direction Express your answer with appropriate units View Available Hint s t Submit Part B 01 A Value n Units Through what angle does the motor turn between t 0 s and the instant at which it reverses direction Express your answer in radians View Available Hint s

Valerie s 186 6 W flat iron is plugged into a 120 V line in her bedroom What current does the flat iron draw

In which situation would current be induced in a wire O the wire moves perpendicular to a magnetic field O the wire moves parallel to a magnetic field the wire stays stationary inside a magnetic field the wire stays stationary above a magnetic field

How is most electricity made O using lightning O mining iron ore O electromagnetic induction O building batteries

Current flows through a wire creating a magnetic field that wraps around the wire as shown If the black line represents the wire in which direction will the current flow X X X down Oright

inal Exam Analytical Problem 3 A person is tied to an electrical generator device as shown in the figure Suppose the person bends themselves of C 2 0 m and are rotated at a rate of w rads s in a magnetic field of strength B 48 www Brushes a Determine an expression for the maximum emf generated by the person s rotation in terms of the frequency of rotation f C and B Hint w 2m and circumference b Next determine an expression for the current generated through the person if their resistance is R c Finally solve this express for the frequency of rotation f and calculate the frequency required to r magnetic field strength is 1 5 T the

Magnetism 1 A wire has a current that is flowing in a direction that is out of the page draw the wire and the magnetic field that it generates 2 Two wires run parallel to one another their currents of electrons are in the same direction Draw the wires and the magnetic field generated by each then determine if they attract or repel one another 3 A wire has a current that is flowing East draw the wire and the magnetic field that it generates above and below the wire

36 A point mass m is located at the origin Let Q be the flux of the gravitational field F Gm through the cylinder x y R for a x b including the top and er 72 bottom Figure 18 Show that Q 47Gm if a 0 b m lies inside the cylinder and Q 0 if 0 a b m lies outside the cylinder b R a m Rogawski et al Multivariable Calculus 4e 2019 W H Freeman and Company

7 The electric force between two particles is 500 N If you move them so that the distance between then is doubled what is the new force between them Hint Use Coulomb s Law 6 pts

2 Two balloons with charges of 2 C and 6 C are separated by a distance of 1 50 m What is the force between the balloons and is this repulsive or attractive force 8 pts

7 An electron with a velocity of 2x10 7 m s enters a magnetic field of 0 1 T at an angle of 60 degrees as shown below What force does the electron experience Charge of electron 1 6x10 19C Hint The angle is important Apply the formula including using sin theta Round decimal to nearest tenth Scientific notation should not have any spaces Electron e 2 x 107 m S 0 60 1F

14 A 4 m long wire with a current of 2 5 A moving from left to right i placed in a magnetic field with a magnitude of 2 T that is directed to the bottom of the page as shown below What is the magnitude of the force experienced by the wire

10 The figure below shows a piece of insulated wire The upper loop has a radius of 6 00 cm the middle loop has a radius of 20 cm and the lower loop has a radius of 2 00 cm The wire has a uniform resistance per unit length of 2 00 Ohm m The wire lies in a plane that is perpendicular to a uniform magnetic field directed into the page the magnitude of which is increasing at a constant rate of 3 00 T s a Find the magnitude of the induced emf ANSWER b Find the magnitude of the induced current in the wire ANSWER c Find the direction of the induced current in the wire ANSWER x