Q1. Is the source of magnetic field analogue to the source of electric field ?
Ans: No. It is because, the source of magnetic field is not a magnetic charge. In case of electric field, the source of electric field is electric charge.
Q2. State Biot Savart's law
Ans: It states that magnetic field due to a small conductor of length dl, carrying a current I at a point at distance r, is given by
dB = μ0/4π × I dl sinθ/r2
Where θ is the angle between the direction of flow of current and the line joining the small conductor to the observation point.
Q3. A conductor carrying current is placed somewhere. What is the magnitude and direction of the field due to a small part of the condutor at a point near it ?
Write Biot Savart expression for the magnetic field due to a current element in vector form.
Ans: It is given by
⃗dB = (μ0/4π) × (I ⃗dI × ⃗r)/ r3
where the letters have their usual meanings
Q4. Name the SI unit of magnetic permeability of free space.
Ans: The SI unit of permeability is weber ampere−1metre-1(Wb A−1m−1) or tesla ampere−1metre (T A−1m)
Q5. What is the value of constant μ0/4π?
Ans: μ0/4π = 10−7 T A−1m
Q6. Write the dimensional formula of μ0 .
Ans: The dimensional formula of μ0 is [M L T −2 A −2]
Q7. State the rule that is used to find the direction of field acting at a point near a current carrying straight conductor.
Ans: Right hand thumb rule can be used to find the direction of magnetic field at a point near a current carrying conductor.
Q8. Does a current carrying circular coil produce uniform magnetic field ?
Ans: No, magnetic field produced due to a current carrying circular coil is not uniform. However, it may be considered as uniform at the centre of the circular coil.
Q9. What is the effect of increasing the number of turns on magnetic field produced due to a circular coil?
Ans: The magnetic field produced by a coil of n turns is n times the magnetic field produced by a coil of single turn.
Q10. Looking at a circular coil, the current is found to be flowing in anticlockwise direction. Predict the direction of magnetic field produced at a point on the axis of the coil on the same side as the observer.
Ans: The direction of magnetic field is perpendicular to the plane of the coil and directed towards the observer.
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