In an electrical circuit, which of the following controls whether or not electrons flow through the circuit?

a. a switch
b. a battery
c. a resistor
d. a light bulb

What type of electromagnetic wave is used in security pens? a. x-rays c. microwaves b. visible light d. ultraviolet radiation select the best answer from the choices provided

A175 g lump of molten lead at its melting point (327 c) is placed into 55.0 g of water at 20.0 c. the specific heat of lead is 130.j/kg c and the hf of lead is 20,400 j/kg. when the lead and the water have reached equilibrium, what is the temperature of the mixture?

The free body diagram shows a box being pulled to the left up a 25-degree incline. the magnitude of the normal force is