What is the dynamo model of Earth's magnetic field?
A. Earth's magnetic field changes too rapidly for it to be generated in Earth's interior.
B. Earth's magnetic field is maintained by convection in the interior of the planet, as well as its rotation.
C. Electric currents in the atmosphere (aurora) generate Earth's magnetic field.
D. Currents in Earth's oceans maintain the planet's magnetic field.
E. None of these choices are correct.
Answer: B
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A bowling ball-size probe from a spaceship and a pebble-size object land on a large asteroid that is far from any star. After a long period of time has passed, it is highly probable that the pebble and the probe
A. have each had the same change in temperature. B. have each had the same change in volume. C. are in thermal equilibrium with one another. D. are not in thermal equilibrium with one another. E. are in thermal equilibrium with one another, but are not at the same temperature.
An important reason for using a very large diameter objective in an astronomical telescope is
A) to increase the magnification. B) to increase the resolution. C) to form a virtual image, which is easier to look at. D) to increase the width of the field of view. E) to increase the depth of the field of view.
The energy stored in a stretched spring is an example of __________ energy
Fill in the blank(s) with correct word
A crate is given an initial speed of 3.0 m/s up the 25.0° plane shown in Fig. 5–33.
(a) How far up the plane will it go?
(b) How much time elapses before it returns to its starting point?
