The Earth's surface has a negative surface charge density of `10^(-9)C//m^2`. The potential difference of 400kV between the top of the atmosphere and the surface, results (due to low conductivity of the lower atmosphere) in a current of only 1800 A over the entire globe. If there is no mechanism of sustaining atmospheric electric field, how much time (roughly) would be required to neutralise the Earth’s surface?

The earth's surface has a negative surface charge density of 10^-9C.m^-2 . The potential difference of 400kV between the top of the atmosphere and the surface results (due to the low conductivity of the lower atmosphere) in a current of only 1800 A over the entire globe. If there wre no mechanism of sustaining atmospheric,electric field, how much time (roughly) would be required to neutralise earth's surface? [Radius of earth = 6.37 times 10^6m ]

The top of the atmosphere is at about 400kV with respect to the surface of the Earth, corresponding to an electric field that decreases with altitude. Near the surface of the Earth, the field is about 100 V/m. Why then we do not get electric shock as we step out of our house into the open ?

Two large, thin metal plates are parallel and close to each other. On their inner faces, the plates have surface charge densities of opposite signs and of magnitude 17.0 xx 10^(-22) C .m^(-2) .What is the electric field between the plate ?

An aeroplane is travelling at the speed of 360 km//hr along the horizontal to the earth surface'. What is the induced potential developed between the ends of th'e wing 5 m long, if the earth’s magnetic field at the location has-a magnitude of 4 xx 10^-4 wb//m^2 and dip angle is 30^@ ?

The top of the atmosphere is at about 440 kV with respect to the surface of the earth, corresponding to an electric field that decreases with altitude. Near the surface of the earth the field is about 100 V cdot m^(-1) . Why then we do not get an electric shock as we step out of our house into the open? (Assume the house to be a still cage so there is no field inside.)

Einstein's equation for photoelectric effect is E_("max") = hf - W_(0) , where h = Planck's constant = 6.625 xx 10^(-34) J.s, f = frequency of light incident on metal surface, W_(0) = work function of metal and E_("max") = maximum kinetic energy of the emitted photoelectrons. It is evident that if the frequency f is less than a minimum value f_(0) or if the wavelength lamda is greater than a maximum value lamda_(0) , the value of E_("max") would be negative, which is impossible. Thus for a particular metal surface f_(0) is the threshold frequency and lamda_(0) is the threshold wavelength for photoelectric emssion to take place. Again if the collector plate is ketp at a negative potential with respect to the emitter plate, the velocity of the photoelectrons would decrease. The minimum potential for which the velocity of the speediest electron becoes zero, is known as the stopping potential, the photoelectric effect stops for a potential lower than this. [velocity of light = 3xx 10^(8) m.s^(-1) , mass of an electron m = 9.1 xx 10^(-31) kg , charge of an electron, e = 1.6 xx 10^(-19)C The threshold wavelength of photoelectric effect for a metal surface is 4600 Å . Work function of the metal (in eV) is