12th Physics Monthly Test - 1 ( Electrostatics )

St. Britto Hr. Sec. School - Madurai

12th Physics Monthly Test - 1 ( Electrostatics )-Aug 2020

Time : 2.30 Hours

Part - A

Multiple Choice Question - Answer All Question

Charge Q is divided into two parts which are then kept some distance apart. The force between them will be maximum if the two parts are

\(\frac{Q}{2} \) each
each \(\frac{Q}{5} \)
\(\frac{Q}{3} \)and\(\frac{2Q}{3} \)
\(\frac{Q}{4} \)and\(\frac{3Q}{4} \)

Near a charged object A another earthed object B is placed. Charges are induced on B. If B is removed. After that the charge on A ________.

remains the same
decreases
increases
becomes zero

The force between like charges is _________.

attraction
repulsion
no force
none

The capacitance of a parallel plate capacitor increases from 5μf of 50μf when a dielectric is filled between the plates. The permitivity of the dielectric is

8.854x10^-12C²N^-1 m^-2
8.854x10^-11C²N^-1 m^-2
10x10^-12C²N^-1 m^-2
12x10^-12C²N^-1 m^-2

Relative permittivity (ε_r) is also known as ________

dielectric strength
dielectric constant
polarisability
susceptibility

The expression for the electric field due to a surface of total charge 'Q' is given by

\(\vec{E}=\frac{1}{4πε_0}∫\frac{σdA}{r^2}\hat{r}\)
\(\vec{E}=\frac{1}{4πε_0}∫\frac{ρdA}{r^2}\hat{r}\)
\(\vec{E}=\frac{1}{4πε_0}∫\frac{λdl}{r^2}\hat{r}\)
\(\vec{E}=\frac{1}{4πε_0}∫\frac{dq}{r^2}\hat{r}\)

The unit for electric flux is

C²N^-1m^-2
Nm²C^-2
Nm²C^-1
Nm^-2C^-1

A positively charged body 'A' has been brought near a brass cylinder 'B' mounted on a glass stand as shown in the figure. The potential of 'B' will be

zero
Negative
positive
Infinite

Torque experienced by a dipole in an electric field when it is placed parallel to the field is ______.
pE sin θ

-pE cosθ

infinity

zero
Two points A and B are maintained at a potential of 7 V and -4 V respectively. The work done in moving 50 electrons from A to B is
8.80 × 10^-17 J

-8.80 × 10^-17 J

4.40 × 10^-17 J

5.80 × 10^-17 J

A polythene piece rubbed with wool is found to have negative charge of 3.2 x 10^-7 C. Estimate the number of electrons transferred from wool to polythene

2x10¹²
3x10¹²
4x10¹²
5x10¹²

The unit for electric susceptibility is

Nm² C^-2
C² N^-1 m^-2
C^-2Nm²
N^-1 m^-2C²

An electric dipole is placed at an alignment angle of 30⁰ with an electric fi eld of 2 × 10⁵ NC^-1. It experiences a torque equal to 8 N m. Th e charge on the dipole if the dipole length is 1 cm is

4 mC
8 mC
5 mC
7 mC

Near a charged object A another earthed object B is placed. Charges are induced on B. If B is removed. After that the charge on A ________.

remains the same
decreases
increases
becomes zero

The expression for electric potentid difference is

\(∫^P_R+\vec{E}.\vec {dr}\)
\(-∫^P_∞+\vec{E}.\vec {dr}\)
\(∫^P_∞+\vec{E}.\vec {dr}\)
\(∫^P_R-\vec{E}.\vec {dr}\)

The value of relative permittivity of air is

8.854 x 10^-12C²N^-1m^-2
9x10⁹C²N^-1m^-2
1
8.854 x 10¹²

Part - B

Generic 2 - Answer All Question

Asphere of charge +Q is fixed. Asmaller sphere of charge +q is placed near the larger sphere and
released from rest. The small sphere will move away from large sphere with
a. decreasing velocity & decreasing acceleration.
b. decreasing velocity & increasing acceleration.
c. decreasing velocity &constant acceleration d. increasing velocity & decreasing acceleration
e. increasing velocity & increasing acceleration
Which of the above statement is correct? Explain.

(i) Two insulated charged copper spheres A & B of identical size have charges qn and -3q_A respectively. When they are brought in contact with each other and then separated. What are the new charges on them?
(ii) When third sphere of some size but uncharged is brought in contact with first and then second and finally removed? What are the new charges.
What are Non-polar molecules

Gauss law is true for any closed surface, no matter what its shape or size is. Justify.

What do you mean by Potential Energy of an electric dipole, when placed in electric field?

Draw equipotential surface
(i) in a uniform electric field and
(ii) for a point charge (Q < 0)

Aparallel plate capacitor is charged by a battery after some time, the battery is disconnected and a dielectric slab with its thickness equal to the plate so reparation is insected between the plates. How will
(i) the capacitance of the capacitor
(ii) potential difference between the plates &
(iii) the energy stored in the capacitor the affected?
Q_o - charge; V_o - potential difference,
C_o - capacitance, E_o- electric field.
U₀ - energy spred, before the dielectric slab is inserted.
\({ Q }_{ 0 }={ C }_{ 0 }{ V }_{ 0 };\frac { { B }_{ 0 } }{ d } ;{ U }_{ 0 }=\frac { 1 }{ 2 } { C }_{ 0 }{ v }_{ 0 }^{ 2 }\)

Define ‘Electric dipole’.

Two charge d spherical conditioners of radii R₁ & R₂ when connected by a conducting wire acquire charges q₁ & q₂ respectively. Find the ratio of surface charge densities in terms of their radii.

Two isolated metal spheres A &B have radii R & 2R respectively and same charge q. Find which of the two spheres have greater energy density just outside the surface of the sphere.
Assertion: Two surfaces of spheres A and B of radii r and r when connected by a wire, form an equipotential surface. i.e V_A = V_B
Reason: Surface charge density (σ) is inversely proportional to the radius of the sphere i.e sx\(\frac{1}{r}\). [as radius is smaller, σ will be larger]

(a) Assertion and Reason are correct and Reason is the correct explanation of Assertion.
(b) Assertion and Reason are true but Reason is the false explanation of the Assertion.
(c) Assertion is true but Reason is false.
(d) Assertion is false but Reason is true.

Give a comparison of electrical and gravitional forces?

Body placed at the centre are shown. Identify the polarity of the charge & draw the electric field lines due to it

What is meant by quantisation of charges?

Two concentric metallic spherical shells of radii Rand 2 R are given charges Q₁ & Q₂ respectively.
The surface charge density on the outer surfaces of the shells are equal. Determine the ratio Q₁ =Q₂.

What is corona discharge?

The electric field due to a point charge depends on the distance r as parallely indicate how each of the following quantities depends on r?
a. Intensity of light from a point source.
b. Electrical potential due to a point charge.
c. Electrical potential at a distance r from to centre of a charged metallic sphere Given r < radius of the sphere.

Part - C

Generic 3 - Answer All Question

What is dielectrics or insulators.

Explain in detail the construction and working of a Van de Graaff generator.

Explain the Lightning arrester or lightning conductor.
Define potential difference and derive.

The following pictures depict electric field lines for various charge configurations.

(i) In figure (a) identify the signs of two
charges and find the ratio \(\left| \frac { { q }_{ 1 } }{ { q }_{ 2 } } \right| \)
(ii) In figure (b), calculate the ratio of two positive charges and identify the strength of the electric field at three points A, B, and C
(iii) Figure (c) represents the electric field lines for three charges. If q₂ = -20 nC, then calculate the values of q₁ and q₃.

What happens when and electric dipole is held in a non-uniform electric field?

Obtain an expression for potential energy due to a collection of three point charges which are separated by finite distances.

How is electric flux is related to electric field.

What is principle used in Microwave oven? Explain.
(a) Calculate the electric potential at points P and Q as shown in the figure below.
(b) Suppose the charge +9μC is replaced by -9μC find the electrostatic potentials at points P and Q.

(c) Calculate the work done to bring a test charge +2μC from infinity to the point P. Assume the charge +9μC is held fixed at origin and +2μC is brought from infinity to P.

Explain dielectrics in detail and how an electric field is induced inside a dielectric.

Deduce electric flus for closed surfaces.

Part - D

Generic 5 - Answer All Question

A network of six identical capacitors, each of value C is made as shown in the figure find the equivalent capacitance between the points A&B.
It requires 50 μJ of work to carry a 2C charge from point R to S. What is the potential difference between these points?

Two point charges having equal charges separated by 1m distance experiences a force of 8N. What will be the force experienced by them, if they are held in water at the same distance?

Obtain Gauss law from Coulomb's law.

The following figure represents the electric potential as a function of x – coordinate. Plot the corresponding electric field as a function of x.

Calculate the electric field due to a dipole on its axial line and equatorial plane.

Comment

Add Comment

InstaQB

Institutions

12th Standard English Medium

12th Standard Tamil Medium

11th Standard English Medium

11th Standard Tamil Medium

10th Standard English Medium

9th Standard English Medium

8th Standard English Medium

7th Standard English Medium

Class XII

Class XI

12Th Standard

11Th Standard

10Th Standard

9Th Standard

12th Physics Monthly Test - 1 ( Electrostatics )

St. Britto Hr. Sec. School - Madurai

12th Physics Monthly Test - 1 ( Electrostatics )-Aug 2020

Part - A

Multiple Choice Question - Answer All Question

Charge Q is divided into two parts which are then kept some distance apart. The force between them will be maximum if the two parts are

Near a charged object A another earthed object B is placed. Charges are induced on B. If B is removed. After that the charge on A ________.

The force between like charges is _________.

The capacitance of a parallel plate capacitor increases from 5μf of 50μf when a dielectric is filled between the plates. The permitivity of the dielectric is

Relative permittivity (εr) is also known as ________

The expression for the electric field due to a surface of total charge 'Q' is given by

The unit for electric flux is

A positively charged body 'A' has been brought near a brass cylinder 'B' mounted on a glass stand as shown in the figure. The potential of 'B' will be

Torque experienced by a dipole in an electric field when it is placed parallel to the field is ______.

Two points A and B are maintained at a potential of 7 V and -4 V respectively. The work done in moving 50 electrons from A to B is

A polythene piece rubbed with wool is found to have negative charge of 3.2 x 10-7 C. Estimate the number of electrons transferred from wool to polythene

The unit for electric susceptibility is

An electric dipole is placed at an alignment angle of 300 with an electric fi eld of 2 × 105 NC-1. It experiences a torque equal to 8 N m. Th e charge on the dipole if the dipole length is 1 cm is

Near a charged object A another earthed object B is placed. Charges are induced on B. If B is removed. After that the charge on A ________.

The expression for electric potentid difference is

The value of relative permittivity of air is

Part - B

Generic 2 - Answer All Question

What are Non-polar molecules

Gauss law is true for any closed surface, no matter what its shape or size is. Justify.

What do you mean by Potential Energy of an electric dipole, when placed in electric field?

Draw equipotential surface (i) in a uniform electric field and (ii) for a point charge (Q < 0)

Define ‘Electric dipole’.

Two charge d spherical conditioners of radii R1 & R2 when connected by a conducting wire acquire charges q1 & q2 respectively. Find the ratio of surface charge densities in terms of their radii.

Two isolated metal spheres A &B have radii R & 2R respectively and same charge q. Find which of the two spheres have greater energy density just outside the surface of the sphere.

Give a comparison of electrical and gravitional forces?

Body placed at the centre are shown. Identify the polarity of the charge & draw the electric field lines due to it

What is meant by quantisation of charges?

Two concentric metallic spherical shells of radii Rand 2 R are given charges Q1 & Q2 respectively. The surface charge density on the outer surfaces of the shells are equal. Determine the ratio Q1 =Q2.

What is corona discharge?

Part - C

Generic 3 - Answer All Question

What is dielectrics or insulators.

Explain in detail the construction and working of a Van de Graaff generator.

Explain the Lightning arrester or lightning conductor.

Define potential difference and derive.

What happens when and electric dipole is held in a non-uniform electric field?

Obtain an expression for potential energy due to a collection of three point charges which are separated by finite distances.

How is electric flux is related to electric field.

What is principle used in Microwave oven? Explain.

Explain dielectrics in detail and how an electric field is induced inside a dielectric.

Deduce electric flus for closed surfaces.

Part - D

Generic 5 - Answer All Question

A network of six identical capacitors, each of value C is made as shown in the figure find the equivalent capacitance between the points A&B.

It requires 50 μJ of work to carry a 2C charge from point R to S. What is the potential difference between these points?

Two point charges having equal charges separated by 1m distance experiences a force of 8N. What will be the force experienced by them, if they are held in water at the same distance?

Obtain Gauss law from Coulomb's law.

The following figure represents the electric potential as a function of x – coordinate. Plot the corresponding electric field as a function of x.

Calculate the electric field due to a dipole on its axial line and equatorial plane.

Comment

Other Study material

12th Physics Monthly Test - 3 ( Magnetism and magn

12th Physics Monthly Test - 1 ( Electromagnetic In

12th Physics Monthly Test - 2 (Current Electricity

12th Physics Monthly Test - 3 ( Current Electricit

12th Physics Monthly Test - 1 ( Magnetism and magn

12th Physics Monthly Test - 2 ( Magnetism and magn

12th Physics weekly Test - 1 ( Communication Syste

Relative permittivity (ε_r) is also known as ________

A polythene piece rubbed with wool is found to have negative charge of 3.2 x 10^-7 C. Estimate the number of electrons transferred from wool to polythene

An electric dipole is placed at an alignment angle of 30⁰ with an electric fi eld of 2 × 10⁵ NC^-1. It experiences a torque equal to 8 N m. Th e charge on the dipole if the dipole length is 1 cm is

Draw equipotential surface
(i) in a uniform electric field and
(ii) for a point charge (Q < 0)

Two charge d spherical conditioners of radii R₁ & R₂ when connected by a conducting wire acquire charges q₁ & q₂ respectively. Find the ratio of surface charge densities in terms of their radii.

Two concentric metallic spherical shells of radii Rand 2 R are given charges Q₁ & Q₂ respectively.
The surface charge density on the outer surfaces of the shells are equal. Determine the ratio Q₁ =Q₂.