What is a device made by joining two different materials to form a circuit that produces an electric current?
a. convertor
b. resistor
c. semiconductor
d. thermocouple

Is there a point between a 10 nc charge and a 20 nc charge at which the electric field is zero?

Astone is dropped from the upper observation deck of a tower, 250 m above the ground. (assume g = 9.8 m/s2.) (a) find the distance (in meters) of the stone above ground level at time t. h(t) = (b) how long does it take the stone to reach the ground? (round your answer to two decimal places.) s (c) with what velocity does it strike the ground? (round your answer to one decimal place.) m/s (d) if the stone is thrown downward with a speed of 2 m/s, how long does it take to reach the ground? (round your answer to two decimal places.) s

Use 4 to 5 complete sentences, explain the concepts of beats and how beats are produces.