A telescope has an angular magnification of 250 when used with a 20 mm eyepiece. What is the focal length of the objective lens?
A) 5.0 cm
B) 25 m
C) 5000 cm
D) 5.0 m
E) 2.5 m
D
You might also like to view...
Mary and Debra stand on a snow-covered roof. They both throw snowballs with the same initial speed, but in different directions
Mary throws her snowball downward, at 30° below the horizontal; Debra throws her snowball upward, at 30° above the horizontal. Which of the following statements are true about just before the snowballs reach the ground below? (There could be more than one correct choice.) A) Debra's snowball will stay in the air longer than Mary's snowball. B) Mary's snowball will stay in the air longer than Debra's snowball. C) Both snowballs will take the same amount of time to hit the ground. D) Debra's snowball has exactly the same acceleration as Mary's snowball. E) Mary's snowball has a greater downward acceleration than Debra's snowball.
A uniform rod (mass = 1.5 kg) is 2.0 m long. The rod is pivoted about a horizontal, frictionless pin through one end. The rod is released from rest in a horizontal position. What is the angular speed of the rod when the rod makes an angle of 30° with the horizontal? (The rotational inertia of the rod about the pin is 2.0 kg/m2)
a. 2.2 rad/s b. 3.6 rad/s c. 2.7 rad/s d. 3.1 rad/s e. 1.8 rad/s
Which element was detected in the Sun before it was found on Earth?
a. Hydrogen b. Promethium c. Helium d. Argon
What causes some asteroids leave the asteroid belt and sometimes approach Earth?
A. Because Earth's gravitational field attracts them. B. Because Jupiter's gravitational field ejects them. C. Because they crash into one another and get ejected.