A concave mirror has a focal length of 20 cm. What is the position (in cm) of the object if the image is upright and is two times larger than the object?
a. 30
b. 20
c. 10
d. 40
e. 60
c
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An iron atom’s nucleus has 26 protons and 30 neutrons. A helium atom’s nucleus has 2 protons and 2 neutrons. Solid iron is much denser than helium gas. How does the total positive charge in a gram of iron compare to that of a gram of helium?
A. Iron has more positive charge than helium per gram. B. Iron has the same positive charge as helium per gram. C. Iron has less positive charge than helium per gram. D. There is not enough information to tell.
The atomic bomb that was dropped on Nagasaki in 1945 killed 140,000 people, helping to end World War II on the next day. It released energy equivalent to that of 20,000 tons of TNT explosive
How much mass was converted to energy when this took place? (1000 tons ? 4.3 × 1012 J) (Incidentally, modern H-bombs have energy yields 1000 times as much!)
A resistor and capacitor are connected in series with an applied AC voltage source. Separate voltmeter readings across the resistor and capacitor give values of 50 V and 60 V (rms), respectively. What is the effective (rms) voltage of the source?
a. 78 V c. 110 V b. 90 V d. 25 V
