A400-turn circular coil (radius = 1.0 cm) is oriented with its plane perpendicular to a uniform magnetic field which has a magnitude that varies sinusoidally with a frequency of 90 hz. if the maximum value of the induced emf in the coil is observed to be 4.2 v, what is the maximum value of the magnitude of the varying magne?

Agenerator converts mechanical energy to electrical energy. when a coil placed between two magnets rotates, the magnetic lines of force are disturbed. this induces a current in the coil. the image below shows a generator. what could be done to make the lamp brighter? a. decrease the size of the magnets b. turn the coil slower c. change the polarity of the magnets d. turn the coil faster

In a thunderstorm, charge builds up on the water droplets or ice crystals in a cloud. thus, the charge can be considered to be distributed uniformly throughout the cloud. for the purposes of this problem, take the cloud to be a sphere of diameter 1.00 kilometer. the point of this problem is to estimate the maximum amount of charge that this cloud can contain, assuming that the charge builds up until the electric field at the surface of the cloud reaches the value at which the surrounding air breaks down. this breakdown means that the air becomes highly ionized, enabling it to conduct the charge from the cloud to the ground or another nearby cloud. the ionized air will then emit light due to the recombination of the electrons and atoms to form excited molecules that radiate light. in addition, the large current will heat up the air, resulting in its rapid expansion. these two phenomena account for the appearance of lightning and the sound of thunder. take the breakdown electric field of air to be eb=3.00ă—106n/c. part a estimate the total charge q on the cloud when the breakdown of the surrounding air is reached. express your answer numerically, to three significant figures, using ďµ0=8.85ă—10â’12c2/(nâ‹…m2) .

Matter is needed to transfer thermal energy bya. conductionb. convectionc. radiation d. both a & b.