A converging lens is kept coaxially in contact with a diverging lens — both the lenses being of equal focal lengths. What is the focal length of the combination?.

Note: the following questions are unrelated to the balmer series or the martian. refer to your course notes. a sun-sized star will spend most of its lifetime as a: white dwarf b. red giant c. protostar d. main-sequence star

What property is a characteristic of a substance that can be observed and does not change the identity of the substance

Suppose a soccer ball is kicked from the ground at an angle 20.0º above the horizontal at 8.00 m/s. the y-velocity is determined to be 2.74 m/s. how long will the ball be in the air? assume the ball lands at the same height at which it was kicked.