## GRE GR 1777, Problem 012 Solution

Physics GRE GR 1777 Quantum Mechanics (Quantum number) The magnetic quantum number can be determined as Thus, the number of allowed values of is . Therefore, when , the number of allowed values of is 5. The answer is (E). References) https://chem.libretexts.org/Core/Physical_and_Theoretical_Chemistry/Quantum_Mechanics/10%3A_Multi-electron_Atoms/Quantum_Numbers https://en.wikipedia.org/wiki/Magnetic_quantum_number

## GRE GR 1777, Problem 011 Solution

Physics GRE GR 1777 11. Quantum Mechanics (Characteristic X-rays) By definition in the Wikipedia, characteristic X-rays are emitted when outer-shell electrons fill a vacancy in the inner shell of an atom, releasing X-rays in a pattern that is “characteristic” to each element. Therefore, the answer is (C). Tips) Actually, I didn’t see this in my…

## GRE GR 1777, Problem 010 Solution

Physics GRE GR 1777 10. Quantum Mechanics (Photoelectric effect) Solution) The maximum kinetic energy of the emitted electrons is , where is the maximum kinetic energy of the emitted electrons from the metal surface, is the frequency of light, and is the work function of the metal. Also, if we want to stop the emitted…

## GRE GR 1777, Problem 009 Solution

Physics GRE GR 1777 9. Classical Mechanics (Kinematics) Solution) , where is the root-mean-square speed of molecules in an ideal gas, is the mass of the molecule, and is the temperature of the system. Since , then . Therefore, . The answer is (D).

## Physics GRE GR 1777, Problem 008 Solution

Physics GRE GR 1777 Problem 008 008. Thermodynamics (Laws of thermodynamics) You should know about First law of thermodynamics where is the amount of heat, is the internal energy, is the pressure, and is the volume of the system. Solution If we want to make a process that the increase in the internal energy is…

## Physics GRE GR 1777, Problem 007 Solution

Physics GRE GR 1777 Problem 007 007. Thermodynamics (Thermodynamic Processes) Solution A reversible process in thermodynamics is a process that has a constant entropy. Answer (C) The entropy of the system and its environment remains unchanged. References https://en.wikipedia.org/wiki/Reversible_process_(thermodynamics)

## GRE GR 1777, Problem 005 Solution

Physics GRE GR 1777 5. Electrodynamics (Maxwell’s Equations) Solution) In Maxwell’s equations, Ampère’s law (with Maxwell’s correction) is . We can write this equation as , where is the current (the electric displacement current). And is change of electric fields with respect to the time (rate of change of the electric flux). If we assume…

## GRE GR 1777, Problem 004 Solution

Physics GRE GR 1777 4. Electrodynamics Solution) Net resistance in a parallel circuit is Then, total resistance in circuit is . By the Ohm’s law, , the total current is , . In a parallel circuit, the current is divided. The ratio of the individual current is the inverse ratio as individual resistance, so ….

## GRE GR 1777, Problem 003 Solution

Physics GRE GR 1777 3. Classical Mechanics (Oscillations) Solution) Angular frequency : Period : In the simple harmonic pendulum, where L is the length of the pendulum. Using above equations, , then we can see that . Since , . Then , therefore . The answer is (E).

## GRE GR 1777, Problem 002 Solution

Physics GRE GR 1777 2. Classical Mechanics (Momentum and Energy) Solution) By the linear momentum conservation, 1) x-direction : 2) y-direction : Therefore, Also, using work-energy theorem, If we assume that all energy generated by collision is converted to heat, then the heat energy produced by the collision is The answer is (E)