Lens-Maker Formula: A double-convex lens made of glass having a refractive index of 1.50 has a radius of magnitude 40 cm on the front side and one of magnitude 30 cm on the back side. What is the focal length of this lens?
A. 11 cm
B. 34 cm
C. 80 cm
D. -240 cm
E. -11 cm
Answer: B
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The second most abundant element in the Earth's atmosphere is
a. oxygen. b. argon. c. nitrogen. d. carbon dioxide.
A battery is attached to several different capacitors connected in parallel. Which of the following statements is true?
1.All capacitors have the same charge, and the equivalent capacitance is greater than the capacitance of any of the capacitors in the group. 2.The capacitor with the largest capacitance carries the smallest charge. 3.The potential difference across each capacitor is the same, and the equivalent capacitance is greater than any of the capacitors in the group. 4.The capacitor with the smallest capacitance carries the largest charge. 5.The potential differences across the capacitors are the same only if the capacitances are the same.
Semiconductors: Metallic bonding is due to
A. the sharing of electrons by all atoms. B. the transfer of electrons between atoms. C. unequal charge distributions around neutral molecules. D. atoms bonding to hydrogen molecules.
When Feynman's two-slit thought experiment is repeated with electrons instead of bullets and water waves, what happens?
a. With one slit open, electrons behave like waves, but with two slits open, they behave like particles. b. Electrons behave like waves, confirming deBroglie's theory. c. Electrons behave like particles, confirming the Bohr model of the atom. d. The electrons act sometimes like waves and sometimes like particles, in no predictable way. e. With one slit open, electrons behave like particles, but with two slits open, they behave like waves.