1. The temperature dependence of resistances of Cu and undoped Si in the temperature range 300-400 K, is best described by
2. An electric motor operating on a 50 V DC supply draws a current of 12 A. If the efficiency of the motor is 30%, then estimate the resistance of the windings of the motor.
3. Cyclotron frequency of an electron circulating in a magnetic field of 1T is
4. The core of a toroid having 3000 turns has inner and outer radii 11 cm and 12 cm, respectively. The magnetic field in the core for a current of 0.70 A is 2.5 T. The relative permeability of the core is
5. An electron of a hydrogen like atom is in excited state. If total energy of the electron is - 4.6 eV, then de-Broglie wavelength of the electron is
6. When a nucleus is in an excited state,
7. In the energy band diagram of material A, conduction band is partially filled and valence band is partially empty and for material B, both conduction and valence band overlaps each other. Then, material A and B respectively are
8. A modern communication system acts as a
9. In a point-to-point communication mode, communication takes place over a link between
10. A singal spreads over a range of frequencies called
