# Electricity and Magnetism-Electrostatics and Magneto-Statics [Optionals IAS Mains Physics]: Questions 1 - 6 of 14

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## Question 1

Electrostatics and Magneto-Statics
Laplace and Poisson Equations

Appeared in Year: 2002

### Describe in Detail

Essay▾

Calculate the electric field for a point on the axis of a charged ring having charge ‘q’ and Radius a show that the maximum value occur at . (20 Marks)

### Explanation

Consider a circular loop of wire of negligible thickness, radius a and centre O held perpendicular to the plane of the paper. Let the loop carry a total charge + q distributed uniformly over its circumference. We have to determine electric field intensity at on axis of the loop, where .

Consider a small element AB of the loop. Let length of element…

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## Question 2

Electrostatics and Magneto-Statics
Energy of a System of Charges

Appeared in Year: 2002

### Describe in Detail

Essay▾

Show that the potential energy of a charge Q uniformly distributed throughout the sphere of radius R is given by (20 marks)

### Explanation

• Let as assume that the sphere has Radius R and ultimately will contain a total charge Q uniformly distributed throughout its volume. The electrostatic potential energy U is equal to the work done in assembling the total charge Q within the volume i.e. the work done in bringing Q from infinity to the sphere. We can do this by bringing a series of ve…

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## Question 3

Electrostatics and Magneto-Statics
Ferromagnetic Materials
Edit

Appeared in Year: 2000

### Describe in Detail

Essay▾

What are the salient features of ferromagnetic? Explain how the curie law of paramagnetism is modified to Curie-Weiss law? (20 Marks)

### Explanation

• Like paramagnetism, ferromagnetism is also associated with the presence of permanent magnetic dipoles, but unlike paramagnetism, the magnetic moments of adjacent atoms in this case are aligned in a particular direction even in the absence of the applied magnetic field. Thus a ferromagnetic material exhibits a magnetic moment in the absence of a mag…

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## Question 4

Electrostatics and Magneto-Statics
Laplace and Poisson Equations
Edit

Appeared in Year: 2007

### Describe in Detail

Essay▾

Obtain the solution of the Laplace equation in cylindrical coordinates. (20 Marks)

### Explanation

• The Laplace equation for the potential V is … eq. (1)
• In cylindrical coordinates Laplace equation is written in the from

… eq. (2)

• From equation (2) it is obvious that the potential function V is a function , hence using the method of separation of variable, we may write

… eq. (3)

• Substituting this in equation (2) , we get

• Dividing above equation by

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## Question 5

Electrostatics and Magneto-Statics
Multiple Expansion of Scalar Potential

Appeared in Year: 2004

### Describe in Detail

Essay▾

A point charge is held at a distance in front of an infinite grounded conducting plane. What is the electric potential in front of the plane?

### Explanation

We suppose that the conducting plane is specified at and the point charge is located at If we imagine a point charge at it is the required image charge for the problem. This is because when we have a pair of equal and opposite point charges, the surface perpendicular to the line joining them and midway between them is a zero potential surface …

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## Question 6

Electrostatics and Magneto-Statics
Potential and Field Due to a Dipole

Appeared in Year: 2016

### Describe in Detail

Essay▾

With the help of a neat diagram, show that the potential due to a dipole at a point is given by , where is the dipole moment of the charge distribution, is the angle between the line joining the centre of the dipole to the point of interest and the axis of the dipole.

### Explanation

Let an electric dipole consist of two equal and unlike point charges at and at , separated by a small distance , with centre at . The dipole moment

Let us take the origin at the centre of the dipole. We have to calculate electric potential at any point where and angle , Fig (1)

Let the distance of from charge at be , i.e. and d…

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