Conceptual questions Class 12 Magnetic effect of current

 MAGNETIC EFFECT OF CURRENT 

1. Is the source of magnetic field an analogue to the source of electric field?

No. The source of electric field is an electric charge but the source of magnetic field is not a magnetic charge.

2. A current is set up in a long copper pipe.  Is there a magnetic field (i) inside (ii) outside the pipe?

(i) The magnetic field is zero inside the pipe.

(ii)  A finite magnetic field exists outside the pipe.

3. Why does a solenoid contract when a current is passed through it?

The current in adjacent turns of the solenoid flows in the same direction. So different turns attract one another and thus the solenoid contracts.

4. Why are the pole pieces of galvanometer made concave?

Concave poles produce strong, uniform and radial magnetic field.

5. What is the main function of soft iron cylinder between the poles of a galvanometer?

Due to the high permeability of soft iron, the magnetic lines of force crowd through the soft iron core which increases the magnetic field and hence the sensitivity of the galvanometer.

6. Where is the magnetic field due to current through circular loop uniform?

At the centre of the loop

7. Where is the magnetic field of a current element minimum?

Along the axis of the current element

8. Where is the magnetic field of a current element maximum?

In a plane passing through the element and perpendicular to its axis

9. What can be the cause of helical motion of a charged particle?

When the charged particle moves inclined (neither zero not 90°) to the magnetic field 

10. Among alpha, beta and gamma radiations, which get deflected by the magnetic field?

Alpha and beta radiations get deflected

11. Why should the spring/suspension wire in a MCG have low torsional constant?

Low torsional constant of the suspension wire ensures high sensitivity of the MCG 

12. The resistance of an ideal ammeter is zero.

13. The resistance of an ideal voltmeter is infinite.

14. Nature of the MCG is radial

Kindly refer textbook for the following questions

15. State

Oersted observation
Biot Savart law
Amperes circuital law

16. Write the formula for

Magnetic field
Magnetic field
1. Due to a straight conductor of finite length
2. Due to an infinitely long straight conductor
3. At the centre of a circular loop
4. At an axial point of a circular loop 
5. At a point well inside the solenoid
6. At either end of the solenoid
7. Inside a toroidal solenoid

Lorentz Force
Force on a moving charge
Force on a current carrying conductor 
Force between parallel current carrying wires
Torque

Formulae related to MCG




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