Electrostatics Concepts and Applications

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Questions and Answers

What is the formula for the magnetic field strength B due to a closed loop carrying current?

B = μ0i / (4πr^2) (correct)

B = μ0 / (4πr)

B = μ0i / (4πr^3)

B = μ0i / (2πr)

What happens to the magnetic field B when θ = 0?

B is at its maximum value.

B equals zero. (correct)

B is equal to μ0i.

B is undefined.

Which rule is used to determine the direction of the magnetic field around a current-carrying wire?

Left Hand Rule

Fleming's Right Hand Rule

Ampere's Law

Right Hand Thumb Rule (correct)

For an infinitely long wire carrying current i, what is the relationship between the magnetic field B and the distance r from the wire?

B is inversely proportional to r. Signup and view all the answers

What value does B attain when θ = 90° in the context of a magnet field calculation?

B is at its maximum value. Signup and view all the answers

What is the formula for the period of revolution (T) related to magnetic fields?

T = 2πm / qB Signup and view all the answers

According to Lenz's Law, what does the induced current do?

Opposes the change in magnetic flux Signup and view all the answers

What happens to the resistance of an ideal ammeter?

Resistance is zero Signup and view all the answers

What is the frequency of revolution (f) formula based on the context provided?

f = qB / 2πm Signup and view all the answers

What is the expression for induced emf (e) as per Faraday's law?

e = -dϕ/dt Signup and view all the answers

How do you convert a galvanometer into a voltmeter?

By connecting high resistance in series Signup and view all the answers

What does motional emf refer to?

Emf induced due to the motion of a conductor in a magnetic field Signup and view all the answers

What is the ideal resistance of a voltmeter?

R = ∞ Signup and view all the answers

What is the formula for the magnetic field on the axial line?

B = 4 r 3 / (μ M) Signup and view all the answers

What happens to the torque acting on a dipole when θ = 90°?

Torque is maximum. Signup and view all the answers

What is the behavior of the magnetic field at the equatorial line?

B is zero. Signup and view all the answers

What is the correct expression for torque acting on a magnetic dipole?

τ = MB sin θ Signup and view all the answers

What is the unit of inductance?

Henry Signup and view all the answers

Which statement describes what happens as temperature decreases in the presence of a magnetic field?

Ferromagnetic substances become paramagnetic. Signup and view all the answers

In the torque formula, what does τ = MB sin θ signify when θ = 0°?

Torque is zero. Signup and view all the answers

Which equation represents the power in an AC circuit?

P = VRMS iRMS Signup and view all the answers

What is the parameter that defines the transition temperature at which a ferromagnetic substance changes behavior?

Curie temperature Signup and view all the answers

What is the shape of the graph plotted between external field (H) and magnetic induction (B)?

BH curve Signup and view all the answers

In which scenario does torque reach its minimum value?

When θ = 0° Signup and view all the answers

What property do freely suspended magnets display?

They rest in N-S direction. Signup and view all the answers

Which type of magnetic material has an odd number of electrons?

Paramagnetic Signup and view all the answers

What does the letter 'L' represent in electromagnetic equations?

Inductance Signup and view all the answers

Which statement describes a property of magnets?

Magnets always have one north and one south pole. Signup and view all the answers

What is the relationship between the number of turns (n) in a solenoid and its magnetic field strength?

More turns increase the magnetic field strength. Signup and view all the answers

What is the unit of electric current?

Ampere Signup and view all the answers

What is the formula for finding the drift velocity (Vd) when initial velocity (u) is zero?

Vd = aτ Signup and view all the answers

What does the symbol 'ρ' represent in the context of electricity?

Resistivity Signup and view all the answers

What is the relationship between current (I), charge (q), and time (t)?

I = q / t Signup and view all the answers

Which factor does not affect the resistivity of a conductor?

Amount of charge Signup and view all the answers

What is the formula for calculating power in electrical systems?

Power = Energy / Time Signup and view all the answers

What does 'J' represent in the equation I = J, where I is current?

Current density Signup and view all the answers

What effect does an increase in temperature generally have on the resistivity of conductors?

Increase in resistivity Signup and view all the answers

What parameter is indicated by 'μ' in the context of electric mobility?

Mobility of charge carriers Signup and view all the answers

What determines the relaxation time (τ) in a conductor?

Temperature of the conductor Signup and view all the answers

What is the formula representing the relationship involving the power of the lens?

$P = \frac{1}{f}$ Signup and view all the answers

What does $I'$ act as for the second lens?

Object Signup and view all the answers

Which equation represents refraction through the first surface?

$\frac{1}{f} = (\mu - 1)(\frac{1}{R_1} - \frac{1}{R_2})$ Signup and view all the answers

What happens when you add equations (i) and (ii)?

It gives the relationship of image distances and focal lengths. Signup and view all the answers

Which of the following represents the final image formed in the lens system?

$I = f_1 + f_2$ Signup and view all the answers

In the context of the lens equation, what does $\mu$ represent?

Refractive index Signup and view all the answers

What does the notation $P = \frac{1}{f(\text{cm})}$ signify?

Power in diopters from focal length in centimeters Signup and view all the answers

Which aspect does equation (1) primarily illustrate?

The effect of the lens curvature on image formation. Signup and view all the answers

Study Notes

Electrostatics

Electric Field Intensity (E): 1 Q / 4πε₀r² (vector)
Electric Potential (V): 1 Q / 4πε₀r (scalar)
Electric Dipole: Equal and opposite charges separated by a small distance. Dipole moment (P) = 2ql (vector).
Torque on Dipole: τ = pEsinθ (where θ is angle between p and E). Maximum torque when θ = 90°.
Energy of Dipole: U = -pEcosθ (negative sign indicates stable when θ = 0)
Gauss's Law: Total electric flux Φ emerges from a closed surface is (1/ε₀) times the enclosed charge. ∫E.dS = Q/ε₀
Electric Field due to long charged wire: E = 2λ / 2πε₀r
Electric Field due to a charged plane sheet: E = σ / 2ε₀ (Independent of distance)
Electric Field due to hollow sphere: E = 0 inside, E = kq/r² outside
Surface charge density (σ): Charge per unit area (C/m²)
Volume charge density (ρ): Charge per unit volume (C/m³)
Capacitance (C) = Charge (Q) / Potential Difference (V), unit is farad
Capacitance for parallel plate capacitor: C = ε₀A/d (where A is the area of the plates and d is the distance between them)
If filled with dielectric, C = kε₀A/d (where k is the dielectric constant)
Energy of Capacitor: U = 1/2 CV² = 1/2 Q² / C.
Energy Density: Energy per unit volume (J/m³) = 1/2 ε₀E²

Current Electricity

Electric Current (I): Charge flowing per unit time (Ampere) = Q/t
Drift Velocity (v): Average velocity of charge carriers due to electric field
Current Density (J): Current per unit area (A/m²) = I/A
Electrical Resistance (R): opposition to current flow
Resistivity (ρ): Resistance of a material per unit length and unit area
Temperature dependence of resistivity
Series combination of resistances: R = R₁ + R₂ + ...
Parallel combination of resistances : 1/R = 1/R₁ + 1/R₂ + ...
Cells in series/ parallel
Wheatstone Bridge: condition P/Q=R/S
Potentiometer: Instrument to measure EMF/ potential difference
Kirchhoff's Laws (junction and loop rules)
Color coding of Resistors
Meter Bridge

Moving Charges and Magnetism

Magnetic Field (B): Vector field produced by moving charges
Ampere's Circuital Law: ∮B ⋅ dl = μ₀I (where I is current enclosed by the loop)
Magnetic field due to infinitely long wire: B = μ₀I / 2πr
Magnetic field inside a solenoid: B = μ₀nI (n is turns per unit length)
Force on a moving charge in a magnetic field: F = qvBsinθ. Lorentz Force
Cyclotron: Device for accelerating charged particles
Force between two parallel current-carrying wires: F = μ₀I₁I₂L / 2πr (where L is length of the wires)
Magnetic field due to a toroid: B = μ₀NI/2πr (where N is total number of turns, I current)

Electromagnetic Induction (EMI)

Faraday's Law of Induction: e = -dΦ/dt (induced emf is proportional to the rate of change of magnetic flux)
Lenz's Law: Induced current opposes the change in magnetic flux that produced it
Motional emf: e = Blv sinθ [Change in flux through a loop by moving the loop]

Magnetism and Matter

Hysteresis loop: Graph of external magnetic field (H) versus magnetic induction (B) during magnetization and demagnetization
Diamagnetism: Materials are weakly repelled by magnetic fields
Paramagnetism: Materials are weakly attracted by magnetic fields
Ferromagnetism: Materials are strongly attracted by magnetic fields and retain their magnetism
Earth's magnetic field: Includes angle of dip and angle of declination; elements of earth's magnetic field, effects

Alternating Current (AC)

AC generators: Convert mechanical to electrical energy (based on EMI)
AC circuits: Pure resistive/inductive/capacitive, and series LCR circuits.
Transformers: Step up/down transformers (based on mutual induction)
RMS (Root Mean Square): Calculation of effective values of AC voltage and current

Ray Optics

Reflection of Light: Laws of reflection, mirrors (concave/convex)
Refraction of Light: Snell's Law, prisms, thin lenses
Lens Maker formula: 1/f = (μ-1) (1/R1 - 1/R2)
Magnification for lenses: m = v/u or h'/h Magnification in mirrors : m = -v/u
Combined Focal Length: 1/f = 1/f₁ + 1/f₂
Power of Lens (optical power): 1/f (in diopter)

Wave Optics

Huygen's Principle: Wavefront construction for light propagation using secondary wavelets
Interference of Light: Resultant intensity from superposition of two coherent light waves; Constructive vs destructive interference; Young's double-slit experiment; Interference pattern calculation; Fringe width.
Diffraction: Bending of light waves around obstacles or through apertures. Single-slit diffraction pattern calculation; Intensity distribution

Dual Nature of Matter and Radiation

Photoelectric effect: Emission of electrons when light shines on a material; Einstein's photoelectric equation; Threshold frequency; Photoelectric current dependence on intensity; maximum KE of emitted electrons
De-Broglie Hypothesis: Associated wavelength with a matter wave

Atom and Nuclei

Rutherford's Scattering Experiment: Nucleus discovery
Bohr Model: Description of the hydrogen spectrum and atomic energy levels; calculation of Bohr radius, energy levels.
Mass energy relationship (E= mc²)
Nuclear Reactions: Fission, Fusion
Radioactivity: Types (alpha, beta, gamma); Radioactive decay laws; half-life; activity

Electronic Devices

Intrinsic/Extrinsic semiconductors, p-n junction
Diodes: Rectifiers, Zener diodes
Transistors: Amplifiers; BJT (different configurations)
Logic Gates: Boolean logic
LEDs, Photodiodes, Solar cells.

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Description

Test your knowledge on key electrostatics concepts, including electric field intensity, potential, dipole moments, and Gauss's Law. This quiz covers essential formulas and principles relevant to understanding electric forces and fields. Perfect for students studying physics at an intermediate level.