Physics
Question from maharashtra board physics book of 12th maharashtra board
- 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
- What will happen if the magnetic field in a moving-coil galvanometer is not radial? Suppose the magnetic field is uniform but not radial. Then, when the coil comes to rest after rotation through an angle θ, NIAB cos θ = Kθ (i... 1
- State under what conditions will a charged particle moving through a uniform magnetic field travel in (i) A charged particle travels undeviated through a magnetic field B if its velocity v is parallel or antiparallel to . In this case, the mag... 1
- Explain why the magnetic force on a charged particle cannot change the linear speed and the kinetic energy The magnetic force on a particle carrying a charge q and moving with a velocity v in a magnetic field of induction B is F_m = q v×B . At ever... 1
- Expression for the Lorentz force on a charge due to an electric field as well as a magnetic field A charge q moving with a velocity through a magnetic field of induction B experiences a magnetic force perpendicular both to B and . v Experi... 1
- Kirchhoff’s first law, i.e., ΣI = 0 at a junction, deals with the conservation of (A) charge Kirchhoff’s first law, i.e., ΣI = 0 at a junction, deals with the conservation of charge 1
- When the balance point is obtained in the potentiometer, a current is drawn from Answer: (C) auxiliary battery only In a potentiometer, the auxiliary battery (driver cell) is connected across the potentiometer wire and ke... 1
- Define Potential Gradient. Potential gradient is defined as the potential difference (the fall of potential from the high potential end) per unit length of the wire. 1