Ascreen is placed between two lamps so that they illuminate the screen equally. the first lamp emits a luminous flux of 1375 lm and is 5 m from the screen. what is the distance of the second lamp from the screen if the luminous flux is 2167 lm? answer in units of m.

Write down two additional questions about earth's magnetic field that will make your presentation more informative.

Air is contained in a variable-load piston-cylinder device equipped with a paddle wheel. initially, air is at 400 kpa and 17°c. the paddle wheel is now turned by an external electric motor until 75 kj/kg of work has been transferred to air. during this process, heat is transferred to maintain a constant air temperature while allowing the gas volume to triple. calculate the required amount of heat transfer in kj/kg.

The electric field direction is defined by the direction of the force felt by (select one of the following answers): 1. a negative charge. 2. a positive charge. 3. both positive and negative charges.