Electric Field and Potential Questions and Answers

26 The length of second s hand in watch is 1 cm The chang in velocity of its tip in 15 seconds is a Zero b c T 30 cm sec d TC 30 2 2 30 cm sec cm sec

the net charge on the object Two spherical balls of the same radius carry charges 0 4 C and 0 9 C Calculate the number of electrons to be transferred from one ball to another uch that they attain the same charge

Two metal spheres one of radius R and the other of radius 2R respectively have the same surface charge density o They are brought in contact and separated What will be the new surface charge densities on them 1 0 2 01 5 60 0 02 5 20 0 02 5 2 3 20 61424 5 2 2 5 6 b 5 3 0 02 3 b

A dipole of dipole moment P is kept at 60 in a non uniform electric field The electri field at the top charge is E and at the bottom is 2E along the same direction What is th total force on the dipole 3PE 1 d 2 PE d 3 3PE 2d 4 zero

Two charges q m and q a massless rod of length of uniform electric field as shown q 1 60 q and released in a region Find the maximum speed of the charges qEl 2m 3qlE 2m L E 2

44 Two point charges q and q of 10 C and 10 C respectively are placed 0 1 m apart 0 1 m 01m 0 05 m 0 05 m 9 9 Then ratio of magnitudes of electric fields at 4 and Cis 49

28 Two small identical spheres having Q and Q charge are kept at a certain distance F force acts between the two If in the middle of two spheres another similar sphere having Q charge is kept then it experience a force in magnitude and direction as c 8F towards Q charge a Zero having no direction b 8F towards Q charge d 4F towards Q charge

11 A Two balls A and B of same mass M and charges Q Q are suspended by two strings of same length from two different suspension points S and S if S S 3x and AB x then show that tension in the string is T Q L 4T EO X 3

5 It is possible that any some constant value of emf but the potential difference between the plates is zero a Not possible b Yes if another identical battery is joined in series c Yes if another identical battery is joined in opposition d Yes possible if another similar battery is joined in parallel

10 A hollow conducting sphere is placed in an electric field produced by a point charge at P as shown in the figure Let VA and VB be the electrostatic potential at points A and B respectively Then 1 VA VB 3 VB VA 3500 B 2 4 A VB VA Relation cannot be determined with the given information

17 Three large non conducting plane sheets of charge with charge densities o 20 and 3o are arranged as shown The net electric field in region III will be 111 III IV 30 1 towards left 0 3 0 2 4 20 0 towards left 30 0 22 towards right

particle of mass m and charge te is projected with velocity v towards a much more massive particle of charge Ze where Z 0 What is the closest possible distance of approach of the incident particle 2 Ze 1 2 mv 3 Ze 2 2 8 omv Ze 2 4 omv 2 4 Ze 2 8 omv

10 Figure shows two equipotential lines in the xy plane for an electric field The scales are marked The x component and y component of the field in the space between these equipotential lines are respectively 1 100 Vm 200 Vm 2 100 Vm 200 Vm 3 200 Vm 100 Vm y cm 3 2 1 0 2 4 12 V 6 V 6 x cm

3 The rms value of potential difference V shown in the figure is V 1 2017 05 N o5 2 3 V T 2 T

dz Figure 31 E12 figure A potential difference V is applied between the points a and b An electron is projected between the plates of the upper capacitor along the central line With what minimum speed should the electron be projected so that it does not collide with any plate Consider only the electric forces

6 A positively charged small disc is released on the top of fixed hemispherical frictionless dome in presence of a uniform horizontal electric field If the disc leaves the dome after an angular displacement 0 sin 3 5 find ratio of gravitational and electrostatic forces on the disc Assume that the dome does not exhibit any electrical property a 4 3 c 9 2 b 3 4 d 12

14 1 2 3 A thin disc of radius b 2a has a concentric hole of radius a in it see figure It carries uniform surface charge o on it If the electric field on its axis at height h h a from its centre is given as Ch then value of C is I aeo 2 0 4a 0

form line of charge with length 20 0 cm is along the z axis with dpoint at x 0 Its charge per length is 6 30 nC m A small re with charge 2 00 C is located at z 0 y 5 00 cm Part A What is the magnitude of the force that the charged sphere exerts on the line of charge Express your answer with the appropriate units F Submit Part B Value Request Answer Units 4 What is the direction angle of the force that the charged sphere exerts on the line of charge The angle is measured from the axis toward the Express your answer in degrees

3 0 2A Thinking 18 marks c www Position 1 2 3 4 5 6 7 8 Battery 4 4V M A 2 501 ww 1 7V Voltage V 7 4 8 6 12 Tv 120 8 4062 0 20 0 20 6 80 W Current Amp W 5 0 2 A 6 7 m Resistance Ohm 50 40

Water from a tap maintained at a constant potential V is allowed to fall by drops of radius r through a small hole into a hollow conducting sphere of radius R standing on an insulating stand until it fills the entire sphere Find the potential of the hollow conductor after it is completely filled with water

k 9 00 x 10 Nm2 C e 1 60 x 10 19 C 1 In the figure at the right four charges are located at the corners of a square whose side is 14 0 cm The charges are qi q3 3 00 uC and q2 94 2 00 C Find the magnitude and direction of the net force on the charge q4 which is located at the origin l da 09

51 A thin film soap bubble of radius R is given a uniform negative charge Q The radius R 1 Becomes 3 Decreases Ka R 2 2 Increases 4 Becomes R

A non conducting ring of radius 0 5 m carries a total charge of 1 11 x 10 10 C distributed non uniformly on its circumference producing an electric field E everywhere in space The value of line integral E de e 0 at the center of the ring in volt L 0 is given potential at infinity is zero Q R 1 2 3 2 d 2 1 4 0

Vo lo k V R 5 00 R8 15 02 R 120 V R3 8 002 V3 13 R 6 0 V Rs 14 02 Vs Is

Application 28 marks a 24V Position 1 2 3 4 5 6 Battery 402 Voltage V 24 202 302 60 Current Amp 892 402 Resistance Ohm 2 3 4 6 8 4

Explain in words how each of these 2 electrons will feel the same electrostatic force in the following situation e

Two small oppositely charged spheres X and Y are fixed in position as shown and have charges of 40 C and 40 C respectively Determine the magnitude and direction of the net electrical force acting on Z in the diagram given due to the charges at points X and Y Z is a 20 C charge 60 15 cm 30 cm

What is the potential difference between y 4cm and yy 4cm in the uniform electric field E 20 0007 25 000 V m Express your answer as an integer and include the appropriate units A D

7 Point charges W X Y and Z each have the same magnitude charge of 6 56 x 106 C Two of the charges are positive as shown and two are negative The corners of the square are 20 0 cm apart Calculate the net force on each of the point charges Draw vector diagrams for each point charge COBJ 7 2 W N 20 0 cm X

m A point particle of charge q 4 5 x 10 6 C is placed on the x axis at x 10 cm A second particle of charge q2 is placed on the x axis at x 25 cm The electric field at the origin is zero Determine the charge 92 KU TA A ring with

3 What is the source of all magnetic fields an isolated magnetic pole moving electric charges charged particles that do not move

The main difference between gravitational and electric forces is that electric forces Select one attract or repel Ob attract C are weaker d obey the inverse square law e act over shorter distances

by occurs when objects are charged without touching

4 The electrostatic force between two point charges is 4 7x10 N If the distance between them is tripled the charge of one of the points triples and the charge of the other point halves What will be the force between them COBJ 7 2

P11 16 2 P 016 90 a Show that the electric field at the center of the triangle is zero Submit a file with a maximum size of 1 MB Choose File No file chosen Three identical point charges each of charge q are located at the vertices of an equilateral triangle as in the figure shown below The distance from the center of the triangle to each vertex is a 9 V This answer has not been graded yet MY NOTES ASK YOUR TEACHER b Find a symbolic expression for the electric potential at the center of the triangle Use any variable or symbol stated above along with the following as necessary ke for the Coulomb s constant c Give a physical explanation of the fact that the electric patential is not zero yet the electric field is zero at the center

8 00 C Need Help 2 00 C 4 00 C a Find the electric potential taking zero at infinity at the upper right corner the corner without a cha ge of the rectangle in the figure Let x 5 30 cm and y 2 90 cm V b Repeat if the 2 00 C charge is replaced with a charge of 2 00 C

Objects 1 and 2 attract each other with a electrostatic force of 72 0 units If the charge of Object 1 is halved AND the charge of object 2 is tripled then the new electrostatic force will be units

An isolated conducting sphere of radius r 0 20 m is at a potential of 2000V with charge Qo The charged sphere is then surrounded by an uncharged conducting sphere of inner radius r 0 40 m and outer radius r3 0 50m creating a spherical capacitor a 5 points Draw a clear physics diagram of the problem b 5 points Determine the charge Qo on the sphere while its isolated c 8 points A wire is connected from the outer sphere to ground and then removed Determine the magnitude of the electric field in the following regions R r r R r2 r2 R r3 r3 R d 3 points Determine the magnitude of the potential difference between the sphere and the conducting shell e 4 points Determine the capacitance of the spherical capacitor

35 The electric field strength of a charge is 3 01 x 10 N C at a distance of 1 78 m Calculate the magnitude of the charge

2 Describe in words the mathematical relationship between electric field charge and electrostatic force 3 Describe in words the mathematical relationship between potential difference charge and work 4 Explain in words how each of these 2 electrons will feel the same electrostatic force in the following situation e

What occurs when two charges are moved closer together Select one O a Coulomb s law takes effect b The force between the charges increases Oc The total charge increases Od The electric field doubles

a e i i I i l A metal rod is brought in contact with the positively charged electroscope A glass rod is charged positively by rubbing it with silk The silk is touched to a neutral electroscope An electroscope is charged by conduction by a positive rod A positively charged rod is brought near but not touching an uncharged electroscope A positively charged rod is brought near a positively charged electroscope A negatively charged rod is brought near a neutral electroscope A positive rod is brought near a neutral electroscope and the electroscope is charged by induction Choose Choose Choose Choose Choose Choose Choose

Particles q1 92 and q3 are in a straight line Particles q 5 00 x 10 6 C q2 2 50 x 10 6 C and q3 2 50 x 10 6 C Particles q and q2 are separated by 0 500 m Particles 92 and 93 are separated by 0 250 m What is the net force on q2

A point charge q is placed at x 0 The electric field at x L is When another charge 4q is placed at x 2L what is the new electric field vector at x L O 3 of O 4E

1 A 12 0 V storage battery is connected to three resistors 6 75 ohm 15 3 ohm and 21 6 ohm respectively The resistors are joined in series a Calculate the equivalent resistance b Find the potential difference across each resistor

positive test charge of 0 41 C experiences a force of 0 45 N What is the magnitude and direction of the electric fielc

The following problem is computer graded your answer needs three digits nonzeros and include the unit A thundercloud has an electric charge of 24 7 C near the top of the cloud and 25 7 C near the bottom of the cloud The magnitude of the electric force between these two charges is 3 95 x 10 N What is the average separation between these charges

A positive test charge of 0 41 C experiences a force of 0 45 N What is the magnitude and direction of the electric field

ind the magnitude and direction of the electric field 0 15 m from a 1 2 x 106 C charge

The d in Coulomb s law is the between the charged particles