12th Science Maharashtra Board
In this category students supposed to ask questions which belong to std 12th maharashtra board Science
- 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
- Currents in two infinitely long, parallel wires exert forces on each other. Is this consistent with Newton’s third law? Yes, they are equal in magnitude and opposite in direction and act on the contrary parts : F _(on 2 by 1) = F _(on 1 by 2). Thus, they form... 1
- What is the fundamental difference between an electric dipole and a magnetic dipole? If a magnet is carefully and repeatedly cut, it would expose two new faces with opposite poles such that each piece would still be a magnet.... 1
- What is an ideal solenoid? A solenoid is a long wire wound in the form of a helix. An ideal solenoid is tightly wound and infinitely long, i.e., its turns are closely... 1
- Choosing different Amperean loops, show that out-side an ideal toroid B = 0. From below figure, the inner Amperean loop does not enclose any current while the outer Amperean loop encloses equal number of I_in and I_ou... 1
- What is an ideal toroid? A toroid is a toroidal solenoid. An ideal toroid consists of a long conducting wire wound tightly around a torus, a doughnut-shaped ring, ma... 1
- Explain Magnetic Dipole Moment A current-carrying coil reacts to an external magnetic field in the same way a magnetic dipole does (or a bar magnet). Like a magnetic dipol... 1
- Advantage of radial magnetic field in a moving-coil galvanometer As the coil rotates, its plane is always parallel to the field. That way, the deflecting torque is always a maximum depending only on the cur... 1