1. A charged particle moving in a magnetic field experiences a force. This force is maximum when the angle between the velocity and the magnetic field is:
Answer:
Explanation:
The magnetic force on a charged particle is given by F = qvBsinθ, where θ is the angle between v and B. The force is maximum when sinθ = 1, which is at θ = 90°.
2. The magnetic field lines inside a solenoid are:
Answer:
Explanation:
Inside a solenoid, the magnetic field lines are parallel and straight due to the closely wound turns of the coil.
3. The SI unit of magnetic field is:
Answer:
Explanation:
The SI unit of magnetic field strength is Tesla.
4. A moving charge produces:
Answer:
Explanation:
According to electromagnetic theory, a moving charge produces both electric and magnetic fields.
5. Ampere's law is related to:
Answer:
Explanation:
Ampere's law relates the integrated magnetic field around a closed loop to the electric current passing through the loop.
6. If an electron is moving in a magnetic field, it experiences a force. The force is zero when the electron moves:
Answer:
Explanation:
The magnetic force on a charged particle is given by F = qvBsinθ. The force is zero when sinθ = 0, which is when the charge moves parallel or anti-parallel to the magnetic field.
7. The magnetic field due to a long straight wire at a distance 'r' from the wire is given by:
Answer:
Explanation:
According to Ampere's law and Biot-Savart law, the magnetic field (B) due to a long straight current-carrying wire at a distance 'r' is given by B = μ₀I/2πr.
8. In a cyclotron, charged particles:
Answer:
Explanation:
In a cyclotron, charged particles accelerate when they cross the gap between the Dees due to an oscillating electric field. Once inside a Dee, they move in circles due to a constant magnetic field.
9. The torque τ experienced by a current loop of area A carrying a current I in a uniform magnetic field B is given by:
Answer:
Explanation:
The torque τ on a current loop in a magnetic field is given by τ = IABsinθ, where θ is the angle between the normal to the loop and the magnetic field.
10. A galvanometer can be converted into an ammeter by:
Answer:
Explanation:
To convert a galvanometer into an ammeter, a low resistance (shunt) is added in parallel to allow most of the current to bypass the galvanometer.
11. Which of the following represents the correct relation between the magnetic field (B), the velocity of a charged particle (v), the charge (q), and the radius (r) of its circular path in a magnetic field?
Answer:
Explanation:
The magnetic force provides the necessary centripetal force for a charge moving in a circular path in a magnetic field. Therefore, qvB = mv²/r which gives B = qv/r.
12. The right-hand thumb rule is used to find:
Answer:
Explanation:
The right-hand thumb rule states that if a current-carrying conductor is grasped with the right hand with the thumb pointing in the direction of the current, then the curled fingers will point in the direction of the magnetic field.
13. A transformer operates on the principle of:
Answer:
Explanation:
A transformer operates on the principle of mutual induction, where a change in current in one coil induces a voltage in a nearby coil.
14. The magnetic field at the center of a current-carrying circular loop of radius R is:
Answer:
Explanation:
The magnetic field (B) at the center of a current-carrying loop is given by B = μ₀I/2R.
15. Magnetic field lines:
Answer:
Explanation:
Magnetic field lines represent the direction of the magnetic field. They never intersect each other because at a point, the magnetic field has a unique direction.
16. A charged particle moving in a magnetic field enters a region where the magnetic field is zero. Its path will be:
Answer:
Explanation:
In the absence of a magnetic field, there will be no magnetic force acting on the particle, and it will continue to move in a straight line.
17. A wire carrying current I is bent into a circle. The magnetic field at its center is:
Answer:
Explanation:
The magnetic field at the center of a current-carrying loop is directly proportional to the current I.
18. Which of the following is not a vector quantity?
Answer:
Explanation:
Magnetic permeability (μ) is a scalar quantity that measures how easily a magnetic field can penetrate a material.
19. The magnetic field lines around a straight current-carrying conductor will be:
Answer:
Explanation:
Around a straight current-carrying conductor, the magnetic field lines are concentric circles with the conductor at the center.
20. Faraday's law of electromagnetic induction states that the induced emf is:
Answer:
Explanation:
Faraday's law states that the induced emf in any closed circuit is equal to the negative rate of change of the magnetic flux through the circuit.