Q2.What is the percentage of the mass of an atom concentrated in the nucleus?
Answer : Option AExplaination / Solution: A proton and a neutron have roughly 2000 times the mass of an electron. The numbers of an electron in a stable atom (not isotope) is equal to the electrons. So for most atoms, the nucleus will hold roughly 4000 times the mass of its electron cloud. Thus,mnucleusmatom=40004001×100%≈99.9%
Q4.A wire is perpendicular to the plane of the paper. A ring of compass needles surrounds the wire in the plane of the paper with center of ring being the center of the wire .Initially there is no current in the wire. What happens after a steady dc current is established in the wire?
Answer : Option AExplaination / Solution: The current carrying wire has a magnetic field around it and the lines of force are in the form of concentric circles with their centers on the wire.
Q8.Basic materials used in the present solid state electronic devices like diode, transistor, ICs, etc are
Answer : Option AExplaination / Solution:
Semiconductors are materials that have electrical conductivity between conductors such as most metals and nonconductors or insulators like ceramics. Semiconductor material is used in the manufacturing of electrical components and used in electronic devices such as transistors and diodes.
Semiconductors are the basic materials used in the present solid state electronic devices like diode, transistor, ICs etc