Electromagnetic Induction And Alternating Currents – NEET UG PhysicsPractice Questions & PYQs

Magnetic flux is defined as the product of the magnetic field strength and the effective area perpendicular to that field, calculated using the relation $\Phi = B A \cos \theta$, where $\theta$ is the angle between the magnetic field vector and the normal to the surface. Since the axis of the disc acts as its normal line, the given angle of sixty degrees represents $\theta$ directly \in the formula. Substituting the disc area computed from a radius of zero point two meters along with the magnetic field into the flux equation gives $\Phi = \left(\frac{1}{\pi}\right) \times (\pi \times 0.2^2) \times \cos 60^\circ$, which simplifies to $0.04$ multiplied by zero point five, yielding zero point zero two webers.

The average power dissipated in an alternating current circuit depends not only on the root-mean-square values of voltage and current but also significantly on the cosine of the phase angle between them. Instantaneous power fluctuates continuously, but the net active power consumed over a full cycle is determined by the expression $P = V_{\text{rms}} I_{\text{rms}} \cos \phi$. Because the resistive component dictates actual energy consumption while reactive components store and return energy, the total power dissipated depends directly on this phase relationship.

The root-mean-square value of a sinusoidal alternating current represents the effective direct current that would produce the same Joule heating effect in a given resistor. This effective magnitude is mathematically defined as the peak current divided by the square root of two. Expressing this relationship yields the standard equation $I_{\text{rms}} = \frac{I_0}{\sqrt{2}}$, which directly connects the maximum amplitude of the waveform to its steady thermal equivalent.