Electric Charge and Coulumb Law
Electric Field
Charge Density And Conductor
Electricty Test Series -1
Electric Potential
Electric Flux and Gauss Law
Electricty Test Series -2
Capacitors I
Capacitors II
Capacitors Test Series
Current Electricity Short Notes-1
Current Electricity Test Series
Sunday, 18 May 2008
IIT JEE Test Series(Electricity-1)
Multiple choice question with only one answer
1.A rod lies along the x-axis with one end at the origin and other at x->∞it caries a uniform charge λ C/m.Find the electric field at the point x=-a on the x-axis
a. -(λ/4πε0a)i
b.-(λ/4πε0a2)i
c. (λ/4πε0a)i
d. (λ/4πε0a2)i
2.Twelve charges of charge q are situated at the corners of the 12 sided polygon of side a.What is the net force on the charge Q at the center
a. Zero
b. 3qQ/πε0a2
c. qQ/πε0a2
d None of the above
3.Two positive point charge are placed at the distance a apart have sum Q.What values of the charges,coulumb force between them is maximum
a.q1=q1=Q/2
b. q1=3Q/4 ,q2=Q/4
c. q1=5Q/6 ,q2=Q/6
d Non of the above
4.A metallic shell having inner radius R1 and outer radii R2 has a point charge Q kept inside the cavity.Electric field in the region R1 < r < R2 where r is the distance from the center is given by
a depends on the value of r
b zero
c, Constant and nonzero everywhere
d. None of the above
5.Consider two statements
A)The force with which two charges interact is not changed by the presence of the other charges
B)Electric force expierenced by the charge particle due to number of fixed point charges is vector resultant of the forces expierence due to individual charges
a) A and B both are correct
b) A is correct only
c) B is correct only
d. A and B both are wrong
Multiple choice question with more than one answer
6)A metallic sold sphere of radius R is given the charge Q.Which of the following statement is true then
a) Electric field at points 0< r < R is zero
b) Charge Q is on the outer surface of the sphere
c) Electric field at r>R is given by Q/4πε0r2
d) Electric field is perpendicular to the surface of the sphere
7)A simple pendulum consists of a small sphere of mass and posutive charge q is suspended by the string of length L.The pendulum is placed in the electric field of strength E directed vertically downwards.Which of the following is true
a)Time period of oscillation=T=2π√L/(g+qE/m)
b)Time period of oscillation=T=2π√L/(g-qE/m)
c) Tension in the string when the pendulum is at rest =mq+qE
d)Tension in the string when the pendulum is at rest =mq-qE
8)A rod lies on the x-axis with end end at x=-L and other end at x=L with uniform charge λ C/m.Which of the following is true
a.Electric field at any point (0,y) on the y-axis is given by
E=(2kλL/y√(y2+L2))j
b. For point on the Y-axis greater than y>>>>L
E=(2kλL/y2)j
c. Electric field if L->∞
E=2kλ/y
d. None of the above
9. A particle of mass m and charge q is thrown horizontally with a velocity v from top of the building of height H.An electric field exists in the plane and it is horizontally away from the building
which of the following is true
a) Range of the particle is greater than v√(2H/g)
b) Time of flight is √(2H/g)
c) Path is parabolic
d None of the above
Assertion and Reason
a) Statement I is true ,statement II is true ,statement II is correct explanation for statement I
b) Statement I is true ,statement II is true ,statement II is not a correct explanation for statement I
c) Statement I is true,Statement II is false
d) Statement I is False,Statement II is True
10.
STATEMENT I:There is no electric field in conducter in electrostatics
STATEMENT II:There are plenty of free electron in the conductor which moves in such a way to cancel all the electric field
11.
STATEMENT I:Coulumb law of forces are a action reaction pair
STATEMENT II:Coulumb law of forces are non conservative in nature
12.
STATEMENT I:Two electric lines of forces never intersect
STATEMENT II:Electric lines of forces originate from -ve charge and terminate on +ve charge
13.
STATEMENT I:Excess charge given to conductor always reside on the outer surface
STATEMENT II:E is zero inside the bulk material of the conductor
Matrix Match type
14) A metallic shell is having a charge q at the center.Column I gives the location of the charge,Column II defines the charge distribution on the surface due to the charge.You have to match the statement in Column I to column II
Column I
A) q is at the center
B) q is displaced from the center
C) An excess charge Q is given to the metallic shell
D) An Charge Q is placed near the shell
Column II
P)Charge distribution is uniform at the inner surface of the metallic shell
Q)Charge distribution is non uniform at the inner surface of the metallic shell
R)Charge distribution is uniform at the outer surface of the metallic shell
S)Charge distribution is non uniform at the outer surface of the metallic shell
Linked Comprehension Type
A electric charge q of mass m is projected horizontally with a velocity v in the Uniform elctric field which occupies limited space in the region.Electric field E is vertically upwards.And the limited region of the electric field is of length a.Assuming X axis as horizontal and Y-axis as vertical.And let us assumes charge start from origin in the electric field.
Answer following question based on this
15)Horizontal components and Vertical components of the velocity when it passes through the end of the field i.e at x=a
a)v,qEa/mv
b)v,qE/mv
c)qEa/mv,a
d)qE/mv,v
16) Equation of the motion of the particle
a) staright line
b) parabola
c) circle
d) none of the above
17) if the charge get deflected by angle α when it comes out of electric field ,then which one is true
a) tanα=qEa/mv2
b) tanα=qEa/mv
c) sinα=qEa/mv
d) sinα=qEa/mv2
Solutions
1.A rod lies along the x-axis with one end at the origin and other at x->∞it caries a uniform charge λ C/m.Find the electric field at the point x=-a on the x-axis
a. -(λ/4πε0a)i
b.-(λ/4πε0a2)i
c. (λ/4πε0a)i
d. (λ/4πε0a2)i
2.Twelve charges of charge q are situated at the corners of the 12 sided polygon of side a.What is the net force on the charge Q at the center
a. Zero
b. 3qQ/πε0a2
c. qQ/πε0a2
d None of the above
3.Two positive point charge are placed at the distance a apart have sum Q.What values of the charges,coulumb force between them is maximum
a.q1=q1=Q/2
b. q1=3Q/4 ,q2=Q/4
c. q1=5Q/6 ,q2=Q/6
d Non of the above
4.A metallic shell having inner radius R1 and outer radii R2 has a point charge Q kept inside the cavity.Electric field in the region R1 < r < R2 where r is the distance from the center is given by
a depends on the value of r
b zero
c, Constant and nonzero everywhere
d. None of the above
5.Consider two statements
A)The force with which two charges interact is not changed by the presence of the other charges
B)Electric force expierenced by the charge particle due to number of fixed point charges is vector resultant of the forces expierence due to individual charges
a) A and B both are correct
b) A is correct only
c) B is correct only
d. A and B both are wrong
Multiple choice question with more than one answer
6)A metallic sold sphere of radius R is given the charge Q.Which of the following statement is true then
a) Electric field at points 0< r < R is zero
b) Charge Q is on the outer surface of the sphere
c) Electric field at r>R is given by Q/4πε0r2
d) Electric field is perpendicular to the surface of the sphere
7)A simple pendulum consists of a small sphere of mass and posutive charge q is suspended by the string of length L.The pendulum is placed in the electric field of strength E directed vertically downwards.Which of the following is true
a)Time period of oscillation=T=2π√L/(g+qE/m)
b)Time period of oscillation=T=2π√L/(g-qE/m)
c) Tension in the string when the pendulum is at rest =mq+qE
d)Tension in the string when the pendulum is at rest =mq-qE
8)A rod lies on the x-axis with end end at x=-L and other end at x=L with uniform charge λ C/m.Which of the following is true
a.Electric field at any point (0,y) on the y-axis is given by
E=(2kλL/y√(y2+L2))j
b. For point on the Y-axis greater than y>>>>L
E=(2kλL/y2)j
c. Electric field if L->∞
E=2kλ/y
d. None of the above
9. A particle of mass m and charge q is thrown horizontally with a velocity v from top of the building of height H.An electric field exists in the plane and it is horizontally away from the building
which of the following is true
a) Range of the particle is greater than v√(2H/g)
b) Time of flight is √(2H/g)
c) Path is parabolic
d None of the above
Assertion and Reason
a) Statement I is true ,statement II is true ,statement II is correct explanation for statement I
b) Statement I is true ,statement II is true ,statement II is not a correct explanation for statement I
c) Statement I is true,Statement II is false
d) Statement I is False,Statement II is True
10.
STATEMENT I:There is no electric field in conducter in electrostatics
STATEMENT II:There are plenty of free electron in the conductor which moves in such a way to cancel all the electric field
11.
STATEMENT I:Coulumb law of forces are a action reaction pair
STATEMENT II:Coulumb law of forces are non conservative in nature
12.
STATEMENT I:Two electric lines of forces never intersect
STATEMENT II:Electric lines of forces originate from -ve charge and terminate on +ve charge
13.
STATEMENT I:Excess charge given to conductor always reside on the outer surface
STATEMENT II:E is zero inside the bulk material of the conductor
Matrix Match type
14) A metallic shell is having a charge q at the center.Column I gives the location of the charge,Column II defines the charge distribution on the surface due to the charge.You have to match the statement in Column I to column II
Column I
A) q is at the center
B) q is displaced from the center
C) An excess charge Q is given to the metallic shell
D) An Charge Q is placed near the shell
Column II
P)Charge distribution is uniform at the inner surface of the metallic shell
Q)Charge distribution is non uniform at the inner surface of the metallic shell
R)Charge distribution is uniform at the outer surface of the metallic shell
S)Charge distribution is non uniform at the outer surface of the metallic shell
Linked Comprehension Type
A electric charge q of mass m is projected horizontally with a velocity v in the Uniform elctric field which occupies limited space in the region.Electric field E is vertically upwards.And the limited region of the electric field is of length a.Assuming X axis as horizontal and Y-axis as vertical.And let us assumes charge start from origin in the electric field.
Answer following question based on this
15)Horizontal components and Vertical components of the velocity when it passes through the end of the field i.e at x=a
a)v,qEa/mv
b)v,qE/mv
c)qEa/mv,a
d)qE/mv,v
16) Equation of the motion of the particle
a) staright line
b) parabola
c) circle
d) none of the above
17) if the charge get deflected by angle α when it comes out of electric field ,then which one is true
a) tanα=qEa/mv2
b) tanα=qEa/mv
c) sinα=qEa/mv
d) sinα=qEa/mv2
Solutions
Saturday, 17 May 2008
Charge Density and conductor
Charge density
Linear charge density
λ=Q/L=dQ/dL
Surface charge density
σ=Q/A=dQ/dA
Volume charge density
ρ=Q/V=dQ/dV
Electrostatics in Conducter
1.E=0 inside the conducter
2. All charge resides on the outer surface of the conducter
3.Electric at the surface is Perpendicular to the surface
Linear charge density
λ=Q/L=dQ/dL
Surface charge density
σ=Q/A=dQ/dA
Volume charge density
ρ=Q/V=dQ/dV
Electrostatics in Conducter
1.E=0 inside the conducter
2. All charge resides on the outer surface of the conducter
3.Electric at the surface is Perpendicular to the surface
Electric Field
Electric field-The region around a particular charge in which its electrical effects can be observed is called the electric field of the charge
-Electric field has its own existence and is present even if there is no charge to experience the electric force.
Electric field Intensity:
E=F/q0
Where F is the electric force experience by the test charge q0 at this point.
It is the vector quantity
Some point to note on this1.Electric field lines extend away from the positive charge and towards thge negative charges
2. Electric field produces the force so if a charge q is placed in the electric field E the force experience by the charge is
F=qE
3 Principle of superposition also applies to electric field
so E=E1+E2+E3+E4+......
Electric field intensity due to point charge
E=KQr/r2
Where r is the distance from the point charge and r is the unit vector along the direction from source to point.
Some useful Formule
Electric field for the Uniformly charged ring
E=KQx/(r2+x2)3/2
Where x is the distance from the center of the ring
At x=0
E=0
Electric Field due to uniformly charged disc
E=(σ/2ε0)(1- x/(√R2+x2))
σ=Surface charge density of the disc
At x=0
E=σ/2ε0
Electric Field Intensity due to Infinite sheet of the charge
E=σ/2ε0
σ=Surface charge density of the sheet
-Electric field has its own existence and is present even if there is no charge to experience the electric force.
Electric field Intensity:
E=F/q0
Where F is the electric force experience by the test charge q0 at this point.
It is the vector quantity
Some point to note on this1.Electric field lines extend away from the positive charge and towards thge negative charges
2. Electric field produces the force so if a charge q is placed in the electric field E the force experience by the charge is
F=qE
3 Principle of superposition also applies to electric field
so E=E1+E2+E3+E4+......
Electric field intensity due to point charge
E=KQr/r2
Where r is the distance from the point charge and r is the unit vector along the direction from source to point.
Some useful Formule
Electric field for the Uniformly charged ring
E=KQx/(r2+x2)3/2
Where x is the distance from the center of the ring
At x=0
E=0
Electric Field due to uniformly charged disc
E=(σ/2ε0)(1- x/(√R2+x2))
σ=Surface charge density of the disc
At x=0
E=σ/2ε0
Electric Field Intensity due to Infinite sheet of the charge
E=σ/2ε0
σ=Surface charge density of the sheet
Electric Charges and Coulumb's Law
- Charges are of two types
(a) positive charge
(b) negative charge
- like charges repel each other and unlike charges attract each other.
-Properties of charge
1. quantisation :- q=ne where n=0,۫, ........ and e is charge of an electron.
2. additivity :- qnet=Σq
3. conservation :- total charge of an isolated system is constant
-Coulumb's law
The mutual electrostatic force between the charges q1 and q2 seperated by a distance r is given by
Force on the charge q1
F1=Kq1q2r12/r2
where r12 is the unit vector in the direction from q2 to q1
similarly force on charge q2 is
F2=Kq1q2r21/r2
where r21 is the unit vector in the direction from q1 to q2
F1+F2=0
If there are more than 2 charges present in the system then force acting on any charges is vector sum of the couloumb force from each of the other charges.This is called principle of superposition
Mathematically
Let q1,q2,q3......qn
charges are present in the system
Then Force on charge q1
F=Kq1q2r12/r122+Kq1q3r13/r132+Kq1q4r14/r142....Kq1qnr1n/r1n2
Similarly for the other charges...
Important point to note on this
1. The force with which two charges interact is not changed by the presence of the other charges
2. Net force on any charge
F=F1+F1+F1+F1....
(a) positive charge
(b) negative charge
- like charges repel each other and unlike charges attract each other.
-Properties of charge
1. quantisation :- q=ne where n=0,۫, ........ and e is charge of an electron.
2. additivity :- qnet=Σq
3. conservation :- total charge of an isolated system is constant
-Coulumb's law
The mutual electrostatic force between the charges q1 and q2 seperated by a distance r is given by
Force on the charge q1
F1=Kq1q2r12/r2
where r12 is the unit vector in the direction from q2 to q1
similarly force on charge q2 is
F2=Kq1q2r21/r2
where r21 is the unit vector in the direction from q1 to q2
F1+F2=0
If there are more than 2 charges present in the system then force acting on any charges is vector sum of the couloumb force from each of the other charges.This is called principle of superposition
Mathematically
Let q1,q2,q3......qn
charges are present in the system
Then Force on charge q1
F=Kq1q2r12/r122+Kq1q3r13/r132+Kq1q4r14/r142....Kq1qnr1n/r1n2
Similarly for the other charges...
Important point to note on this
1. The force with which two charges interact is not changed by the presence of the other charges
2. Net force on any charge
F=F1+F1+F1+F1....
Thursday, 8 May 2008
Study Tips for IITJEE
PART 1
1. Concentrate on the basic concepts.Strengthen your fundamentals.Master the basic of each chapter.Do many times so that you know the concept by heart.NCERT books are good for the concept.So first should be to study the NCERT books and familarize all the concepts.HC verma is also good for concept
2. Once you are through with the concepts,you need to develop problem solving skills.Pick one good physics and start solving the questions.Initially problems of low level should be tried and only when you have mastered them,you should go on to solving intricate JEE type problems.ALways give full attempt the question before seeing the solutions.Try to recall all the formula,concepts and try the solve the problems.Dont take too many Physics books .One or two should be sufficent.
3.JEE paper consists of questions from various units.Some units are easiar to solve.So Students should try the following order for mastering the units
Thermodynamics:It is quite simple to master this topics.JEE paper always have few question from it.So easy to score those.
Hydrostatics and Bernoulli's Principle:This is also simple.
Waves in Elastic Media:THis too is simple to master.JEE always have one or two question from it.
Interference Beats and Doppler's Effect:Similarly for this.
Electrostatics :Coloumbs law,Potential,electric question are simple to attempt.
Electromagnetic Induction
Lorentz' Forces:Simple question from it.
Circuits with Capacitors:Easier to attempt with some practice and method to solve the circuits
Modern Physics (full):Always have some question from it.Easiar to master
Collisions:JEE paper have difficult question from this but easiar then below topics.It should attempted in the last
Rotational Motion:bit tough.It should attempted in the last
Gravitation, Elasticity, S.H.M. :bit tough.It should attempted in the last
4 Once you are through with the course.You should start taking Mock test.This will give you the feel of the examination.Try to give as many as possible.Judge your speed and accuracy.You wont feel tensed and stressed on the examination day this way.
5.Make shorts notes for last revision before examination.Those should contains all the important formule which will help you in solving the problems fast.
6. Develop an habbit of judgeing the question .You should be able to judge the question whether you should go for it or not.This is very important thing.There will always few question in JEE paper which will be very tough.If you put your head in those question,you will waste your time and you will not any thing.SO it is important to judge the question.You should never attempt any question which you dont know head and tail of it.
7.Before starting doing the IITJEE paper
Step 1: Take a quick glance of the paper so that you are aware what all type of question and what all topics are given.It should be done in first three minutes
Step 2:Search for questions of topics which is strong to you.Read the questions of the topics and if you have done similar type of question and you are confident about it.Attempt that question.Do this for all the topics u are strong in
You will always find few questions in this catogory
Step 3:Now try to find the questions in your strong topics which looks easy and solvable to you
Step 4: Try to find easy and solvable question to u in the topics you are not very strong
Please take a look at these post also
Physics Syllabus
Books for IITJEE Physics
Books for AIEEE Physics
1. Concentrate on the basic concepts.Strengthen your fundamentals.Master the basic of each chapter.Do many times so that you know the concept by heart.NCERT books are good for the concept.So first should be to study the NCERT books and familarize all the concepts.HC verma is also good for concept
2. Once you are through with the concepts,you need to develop problem solving skills.Pick one good physics and start solving the questions.Initially problems of low level should be tried and only when you have mastered them,you should go on to solving intricate JEE type problems.ALways give full attempt the question before seeing the solutions.Try to recall all the formula,concepts and try the solve the problems.Dont take too many Physics books .One or two should be sufficent.
3.JEE paper consists of questions from various units.Some units are easiar to solve.So Students should try the following order for mastering the units
Thermodynamics:It is quite simple to master this topics.JEE paper always have few question from it.So easy to score those.
Hydrostatics and Bernoulli's Principle:This is also simple.
Waves in Elastic Media:THis too is simple to master.JEE always have one or two question from it.
Interference Beats and Doppler's Effect:Similarly for this.
Electrostatics :Coloumbs law,Potential,electric question are simple to attempt.
Electromagnetic Induction
Lorentz' Forces:Simple question from it.
Circuits with Capacitors:Easier to attempt with some practice and method to solve the circuits
Modern Physics (full):Always have some question from it.Easiar to master
Collisions:JEE paper have difficult question from this but easiar then below topics.It should attempted in the last
Rotational Motion:bit tough.It should attempted in the last
Gravitation, Elasticity, S.H.M. :bit tough.It should attempted in the last
4 Once you are through with the course.You should start taking Mock test.This will give you the feel of the examination.Try to give as many as possible.Judge your speed and accuracy.You wont feel tensed and stressed on the examination day this way.
5.Make shorts notes for last revision before examination.Those should contains all the important formule which will help you in solving the problems fast.
6. Develop an habbit of judgeing the question .You should be able to judge the question whether you should go for it or not.This is very important thing.There will always few question in JEE paper which will be very tough.If you put your head in those question,you will waste your time and you will not any thing.SO it is important to judge the question.You should never attempt any question which you dont know head and tail of it.
7.Before starting doing the IITJEE paper
Step 1: Take a quick glance of the paper so that you are aware what all type of question and what all topics are given.It should be done in first three minutes
Step 2:Search for questions of topics which is strong to you.Read the questions of the topics and if you have done similar type of question and you are confident about it.Attempt that question.Do this for all the topics u are strong in
You will always find few questions in this catogory
Step 3:Now try to find the questions in your strong topics which looks easy and solvable to you
Step 4: Try to find easy and solvable question to u in the topics you are not very strong
Please take a look at these post also
Physics Syllabus
Books for IITJEE Physics
Books for AIEEE Physics
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