# Magnetic effect of current | Old is Gold | XII

#### Short Questions

1. Under what conditions do a charge affect a magnet?

2. State Ampere’s theorem

3. Does a charged particle moving through a magnetic field experience a force? Express with conditions, maximum, and minimum force it experiences.

4. A portion moving in a straight line enters a strong magnetic field along the field direction. How will its path and velocity change?

5. Why is the cylindrical core of soft iron used in moving coil galvanometer?

6. Define an Ampere in terms of the force between current carrying conductors.

7. How magnetic field is made radial in a moving coil galvanometer?

8. Explain how the direction of Lorentz force is determined.

9. A current carrying solenoid tends to contract, why?

10. A solenoid tends to contract when a current passes through it, why?

11. What will be the effect if the magnetic field in a moving coil galvanometer is not radial?

12. An electron beam and a portion beam are moving parallel to each other is the beginning. Do they always maintain this status? Justify your answer.

13. Deduce an expression for the force between two parallel current carrying conductors. Define one ampere current.

14. State Ampere`s circuital theorem.

#### Long Questions

1. State Biot-Savart law and obtain the expression for the magnetic field at the centre of the circular coil.

2. Explain in brief, the motion of an electron moving normal to a magnetic field.

3. Derive an expression for the magnitude of the magnetic flux density at the centre of a narrow circular coil.

4. Derive an expression for the magnetic field at a point due to a long straight conductor carrying current.

5. What is a Helmholtz coil? Derive an expression for the magnetic field due to this coil.

6. Derive the formula for the magnetic field at the centre of the circle of a circular coil carrying current. Explain why the magnetic field at the centre of the coil disappears when the circular coil is made infinitely large.

7. State and explain Ampere`s theorem and hence use it to find the magnetic field intensity due to a long current carrying solenoid.

8. Derive the formula for the magnetic field at a point due to a long straight current carrying conductor using Biot- Savart law.

9. State and explain Biot-Savart law and hence use it to find the magnetic field intensity at any point due to a long straight conductor.

10. Find an ex expression for torque on rectangular coil in a uniform magnetic field.

11. What is a Helmholtz coil? Derive an expression for the magnetic field due to this coil.

12. State and explain Biot-Savart law. Use this law to find the magnetic field intensity at any point due to a long straight current carrying conductor.

13. State and explain Boit-Savart law with a case of its application.

14. Derive an expression of force per unit length between two parallel conductors separated by distance ‘r’ and carrying currents l

_{1}and l_{2}in the same direction.15. State and explain Biot-Savart law. Use it to find the magnetic field at the center of a circular coil of N turns and carrying current l.

16. Find an expression for the magnetic field on the axis of a solenoid, carrying current, using Ampere`s law.

17. Obtain magnetic field straight at a point on the axis of circular current loop by using Biot and Savart law.

18. State and explain Ampere`s theorem and hence use it to find the magnetic field due to a long solenoid carrying current l.

19. Straight and explain Biot-Savart law and hence use this law to find the magnetic field to a long straight current carrying conductor.

20. What is a Helmholtz coil? Derive an expression for the uniform magnetic field obtained from it.