An electron in a cathode-ray beam passes between 2.5cm long parallel-plate electrodes that are 6.0mm apart. a 2.1mt, 2.5-cm-wide magnetic field isperpendicular to the electric field between the plates. the electron passes through the electrodes without being deflected if the potential difference between the plates is 700v.

part a: what is the electron's speed? (express your answer to two significant figures and include the appropriate units.)

part b: if the potential difference between the plates is set to zero, what is the electron's radius of curvature in the magnetic field? (express your answer to two significant figures and include the appropriate units.)

If you quadruple the temperature of a black body, by what factor will the total energy radiated per second per square meter increase? 1,024 64 16 4 256 submit answer

The sun generates both mechanical and electromagnetic waves. which statement about those wave is true?

Under conditions for which the same room temperature is maintained by a heating or cooling system, it is not uncommon for a person to feel chilled in the winter but comfortable in the summer. provide a plausible explanation for this situation (with supporting calculations) by considering a room whose air temperature is maintained at 20â°c throughout the year, while the walls of the room are nominally at 27â°c and 14â°c in the summer and winter, respectively. the exposed surface of a person in the room may be assumed to be at a temperature of 32â°c throughout the year and to have an emissivity of 0.90. the coefficient associated with heat transfer by natural convection between the person and the room air is approximately 2 w/m2 â‹…â‹… k. what is the ratio of the thermal resistance due to convection to the thermal resistance due to radiation in the summer? what is the ratio of thermal resistances in the winter