At room temperature, electrons cannot escape the metal surface due to ………….. of atomic nucleus:
Repulsive forces
Attractive forces
Gravitational forces
Electromagnetic forces
The refractive index of ice is:
1.00
1.33
1.31
2.42
Which is the most suitable means of reliable continuous communication between an orbiting satellite and earth:
Mecrowaves
Radio waves
Sound waves
Any light waves
What does a switch do:
Oppose the current
Open and close the circuit
Store energy
Provide voltage
First voice signal was transmitted in the form of electrical signal in:
1870
1875
1876
1880