- When the coil is rotated between the pole pieces of a magnet as shown, how often will the magnetic flux linked with the coil be maximum and minimum during one complete rotation of the coil?
Ans: According to Faraday’s law when the magnetic flux linking a circuit changes, an electromotive force is induced in the circuit proportional to the rate of change of the flux linkage.
So, when rectangular coil is rotated in a uniform magnetic field about an axis passing through its centre and perpendicular to the direction of the field, then the induced voltage in the coil =dtdϕ ⇒ e.m.f= dϕ
⇒ e.m.f = NABωcosθ
where θ is the angle between the plane of the coil and the lines of force.
So, the induced emf in the coil is maximum when cosθ is maximum or θ is zero means when the plane of the coil is parallel to the field.
- A rectangular loop has dimensions of 0.50m and 0.60m. The values of B are 0.02T and 45°, respectively. Calculate the magnetic flux at the surface.
Ans: Given:
Dimensions of rectangular loop = 0.50m and 0.60m,
B = 0.02T
θ = 45°
Magnetic flux formula is given by
ΦB = B A Cosθ
Area, A = 0.50 × 0.60
= 0.3 m2
ΦB = 0.02 × 0.3 × Cos 45
ΦB = 0.00312 Wb
- A perpendicular field of force of magnitude 0.1 T is applied to an oblong loop with dimensions of three cm by 5 cm. How does one calculate the magnetic flux through the loop?
Ans: With formula ΦB = BACosθ, magnetic flux is defined because of the product of field, area, and therefore the angle between B and a unit vector perpendicular to the surface.
Here, the loop is positioned perpendicular to the force field B, namely the angle between B and a unit vector normal to the surface n is zero θ = 0⁰. Therefore, applying the formula we get,
=(0.1)(0.03×0.05)cos0∘
=15×10⁻⁻⁵
Wb =0.15 Wb
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