All questions
- What does the hysteresis loop represents? A magnetic hysteresis loop is a closed curve obtained by plotting the magnetic flux density B of a ferromagnetic material against the corres... 1
- Explain one application of electromagnet. Applications of an electromagnet: Electromagnets are used in electric bells, loud speakers and circuit breakers. Large electromagnets are us... 1
- When a plate of magnetic material of size 10 cm × 0.5 cm × 0.2 cm (length , breadth and thickness respectively) Answer: B ≈ 0.635\ T Volume of the plate: V = 10 × 0.5 × 0.2 = 1\ mathrmcm³ = 1×10⁻⁶\ mathrmm³ Magnetisation (magnetic moment per unit volum... 1
- A rod of magnetic material of cross section 0.25 cm2 is located in 4000 Am-1 magnetising field Data: A = 0.25 cm² = 25 × 10⁻⁶ m², H = 4000 A∙m⁻¹, Φ = 25 × 10⁻⁶ Wb Magnetic induction is B = φ/A=frac25 × 10⁻⁶25 × 10⁻⁶ = 1 Wb/m² (a) B = µ... 1
- The work done for rotating a magnet with magnetic dipole momentm, through 90° from its magnetic meridian is n Data : θ₀ = 0°, θ₁ = 90°, θ₂ = 60°, W₁ = nW₂ The work done by an external agent to rotate the magnet from θ₀ to θ is W = MB (cos θ₀ – cos θ)... 1
- An electron in an atom is revolving round the nucleus in a circular orbit of radius 5.3 × 10-11 m, with a speed Data: r = 5.3 × 10⁻¹¹ m, v = 2 × 10⁶ m/s, e = 1.6 × 10⁻¹⁹ C, m_e = 9.1 × 10⁻³¹ kg The orbital magnetic moment of the electron is M₀ = 1/2 ev... 1
- A paramagnetic gas has 2.0 × 1026 atoms/m with atomic magnetic dipole moment of 1.5 × 10-23 A m2 each. Data: N/V = 2.0 × 10²⁶ atoms/m³, μ = 1.5 × 10⁻²³ Am2, T = 27 + 273 = 300 K, B = 3T, k^B = 1.38 × 10⁻²³ J/K, 1 eV = 1.6 × 10⁻¹⁹ J (a) The max... 1
- A magnetic needle placed in uniform magnetic field has magnetic moment of 2 × 10-2 A m2, and moment of inertia Data: M = 2 × 10⁻² A∙m², I = 7.2 × 10⁻⁷ kg∙m², T = 6/10 = 0.6 S T = 2π √(I/M B) The magnitude of the magnetic field is B = frac4 π² IM T² =... 1
- A short bar magnet is placed in an external magnetic field of 700 guass. When its axis makes an angle of 30° Data : B = 700 gauss = 0.07 tesla, θ = 30°, τ = 0.014 N∙m τ = MB sin θ The magnetic moment of the magnet is M = τ/B sin θ=frac(0.014)(0.07)(... 1
- Classify the following atoms as diamagnetic or paramagnetic. H, O, Zn, Fe, F, Ar, He Atoms Electronic configuration No. of Electrons Diamagnetic/Paramagnetic H 1s¹„ 1 Diamagnetic 0 1s²2s²2p⁴ 8 Paramagnetic Zn 1s²2s²2p⁶3s²3p⁶3... 2
- A piece of straight wire has mass 20 g and length 1m. It is to be levitated using a current of 1 A flowing through Data: m = 20 g = 2 × 10⁻² kg, l = 1 m, I = 1 A, g = 9.8 m/s² To balance the wire, the upward magnetic force must be equal in magnitude to th... 1
- Calculate the value of magnetic field at a distance of 2 cm from a very long straight wire Data : I = 5A, a = 0.02 m, fracμ₀4 π = 10⁻⁷ T∙m/A The magnetic induction, B = fracμ₀ I2 π a=fracμ₀4 π 2 I/a = 10⁻⁷ × frac2(5)2 × 10⁻² = 5 ×... 1
- Two wires shown in the figure are connected in a series circuit and the same amount of current of 10 A Data: I₁ = I₂ = 10 A, s = 8 mm = 8 × 10⁻³ m, l = 0.22 m By right hand grip rule, the direction of the magnetic field overrightarrowB₂ due to... 1
- A very long straight wire carries a current 5.2 A. What is the magnitude of the magnetic field Data : I = 5.2 A, a = 0.031 m, fracμ₀4 π = 10⁻⁷ T∙m/A The magnetic induction, B = fracμ₀ I2 π a=fracμ₀4 π 2 I/a = 10⁻⁷ × frac2(5.2)3.1 × 10⁻... 1
- Magnetic field at a distance 2.4 cm from a long straight wire is 16 µT. What must be current through the wire? Data: a = 2.4 × 10⁻² m, B = 1.6 × 10⁻⁵ T, fracμ₀4 π = 10⁻⁷ T∙m/A B = fracμ₀ I2 π a=fracμ₀4 π 2 I/a The current through the wire, I = frac1μ₀... 1
- A circular coil of wire is made up of 100 turns, each of radius 8.0 cm. If a current of 0.40 A Data: N = 100,R = 8 × 10⁻² m, I = 0.4A, µ₀ = 4π × ⁻⁷ T∙m/A B = fracμ₀ N I2 R = frac(4 π × 10⁻⁷)(100)(0.4)2(8 × 10⁻²) = 3.142 × 10⁻⁴ T 1
- For proton acceleration, a cyclotron is used in which a magnetic field of 1.4 Wb/m2 is applied Data: B = 1.4 Wb/m², m = 1.67 × 10⁻²⁷ kg, q = 1.6 × 10⁻¹⁹ C T = 2 π m/q B t = T/2=π m/q B=frac(3.142)(1.67 × 10⁻²⁷)(1.6 × 10⁻¹⁹)(1.4) = 2.34... 1
- A moving coil galvanometer has been fitted with a rectangular coil having 50 turns and dimensions 5 cm × 3 cm. Data : N = 50, C = 1.5 × 10⁻⁹ Nm/degree, A = lb = 5 cm × 3 cm = 15 cm² = 15 × 10⁻⁴ m², B = 0.05Wb/m², θ = 30° NIAB = Cθ ∴ The current throug... 1
- A solenoid of length π m and 5 cm in diameter has winding of 1000 turns and carries a current of 5 A Data: L = 3.142 m, N = 1000, I = 5A, μ₀ = 4π × 10⁻⁷ T∙m/A The magnetic induction, B = μ₀ nI = μ₀( N/L )I = (4π × 10⁻⁷)( 1000/3.142 )(5) = fr... 1
- A toroid of narrow radius of 10 cm has 1000 turns of wire. For a magnetic field of 5 × 10-2 T along its axis Data : CentraI radius, r = 10 cm = 0.1 m, N = 1000, B = 5 × 10⁻² T, = 4π × 10⁻⁷ T∙m/A The magnetic induction, B = fracμ₀ N I2 π r=fracμ₀4 π... 1
- In the above problem, what will be the magnetic field B inside the wire at a distance r from its axis Figure shows the cross section of a long straight wire of radius a that carries a current I out of the page. Because the current is uniforml... 1
- Distinguish between the forces experienced by a moving charge in a uniform electric field A charge q moving with a velocity v through a magnetic field of induction B experiences a magnetic force perpendicular both to B and v . Exp... 1
- What is special about a radial magnetic field ? Why is it useful in a moving coil galvanometer ? Advantage of radial magnetic field in a moving- coil galvanometer: As the coil rotates, its plane is always parallel to the field. That way,... 1
- State Ampere’s law. Explain how is it useful in different situations. Ampere's circuital law : In free space, the line integral of magnetic induction around a closed path in a magnetic field is equal to p0 time... 1