Two identical glass (μg = 3/2) equiconvex lenses of focal length f each are kept in contact. The space between that two lenses in filled with water (μw = 4/3). The focal length of the combination is
A 100 Ω resistance and a capacitor of 100 Ω reactance are connected in series across a 220 V source. When the capacitor is 50% charged, the peak value of the displacement current is
The potential differences across the resistance, capacitance and inductance are 80 V, 40 V and 100 V respectively in an L-C-R circuit. The power factor of this circuit is
A uniform magnetic field is restricted within a region of radius r. The magnetic field changes with time at a rate dB / dt . Loop 1 of radius R > r encloses the region r and loop 2 of radius R is outside the region of magnetic field as shown in the figure below. Then the e.m.f. generated is :
Which of the following combinations should be selected for better tuning of an L-C-R circuit used for communication?
An electron is moving in a circular path under the influence of a transverse magnetic field of 3.57 × 10–2 T. If the value of e/m is 1.76 × 1011 C/kg, the frequency of revolution of the electron is :
