JNTUH
JNTUH B.Tech II ELECTROMAGNETIC FIELDS Previous Question Paper (August/September - 2022 - R15)
Answer any five questions. All questions carry equal marks.
Main
State and Explain Coulomb’s Law.
Answer
Coulomb’s Law states that the force between two point charges is directly proportional to the product of the magnitudes of the charges and inversely proportional to the square of the distance between them. The force acts along the line joining the two charges.
In this expression, Q1 and Q2 are the point charges in Coulombs, R is the distance between them in meters, ε0 is the permittivity of free space (8.854 × 10-12 F/m), and aR is the unit vector directed from the source charge toward the test charge. The force is repulsive for like charges and attractive for unlike charges.
A Eight point charges of 1nC each are located at the corners of a cube in free space that is 1m on a side. Find at the centre of a face.
Answer
For a cube of side length a = 1m with charges q = 1nC at each corner, consider the center of the top face. Let the coordinates of the corners be (0,0,1), (1,0,1), (0,1,1), (1,1,1) for the top face and (0,0,0), (1,0,0), (0,1,0), (1,1,0) for the bottom face. The center of the top face is at (0.5, 0.5, 1).
- The four charges on the top face corners are at distances of √(0.52 + 0.52) = 1/√2 m from the center. Due to symmetry, the horizontal components of the forces from these four charges cancel out, and their vertical components are zero as they lie in the same plane.
- The four charges on the bottom face corners are at a distance r from the center, where r = √(0.52 + 0.52 + 12) = √1.5 m.
- The electric field E from one bottom corner charge is E = q / (4πε0r2). The vertical component is Ez = E cos(θ), where cos(θ) = 1/√1.5.
- Summing the vertical components of the four bottom charges: Etotal = 4 × [q / (4πε0(1.5))] × (1/√1.5).
- Substituting q = 10-9 C and 1/(4πε0) = 9 × 109: Etotal = 4 × (9 × 109 × 10-9 / 1.5) × (1/1.2247) ≈ 19.59 V/m.
Derive expression for potential and Electric field intensity due to an electric dipole.
Answer
Sign in to view the complete answer paper.
An electric dipole, 1az nC-m is at (0, 0, 0). Find the electric field at (0, 0, 1).
Answer
Sign in to view the complete answer paper.
Derive an expression for the capacitance of parallel plate capacitor with composite dielectrics.
Answer
Sign in to view the complete answer paper.
A unit vector directed from region 1 to region 2 at the planar boundary between two perfect dielectrics is given. Find the necessary field components.
Answer
Sign in to view the complete answer paper.
State and Explain Biot Savart’s Law.
Answer
Sign in to view the complete answer paper.
Find H at the centre of square current loop of side ‘L’.
Answer
Sign in to view the complete answer paper.
State Ampere’s Law and explain how do you find H using ampere’s Law.
Answer
Sign in to view the complete answer paper.
A current filament of 5.0A in the ay direction is parallel to the y-axis at x = 2m, z = -2m. Find H at the origin.
Answer
Sign in to view the complete answer paper.
Derive the expression for force between two current carrying Conductors in same direction.
Answer
Sign in to view the complete answer paper.
A conductor of length 2.5m located at z = 0, x = 4m carries a current of 12.0A in the -ay direction. Find the uniform B in the region if the force on the conductor is 1.20 × 10-2N.
Answer
Sign in to view the complete answer paper.
Define Scalar magnetic potential and List out its limitations.
Answer
Sign in to view the complete answer paper.
Determine self-inductance of a solenoid.
Answer
Sign in to view the complete answer paper.
Calculate the self-inductances and mutual inductances between two coaxial solenoids of radius R1 and R2.
Answer
Sign in to view the complete answer paper.
Derive Maxwell’s Equation from Faraday’s law for time varying fields.
Answer
Sign in to view the complete answer paper.
In a material for which σ = 5.0 S/m and εr = 1 the electric field intensity is E = 250 sin 1010t (V/m). Find the conduction and displacement current densities.
Answer
Sign in to view the complete answer paper.