## GRE Physics GR 1777, Problem 022 Solution

GRE Physics GR 1777 Problem Solution 022. Quantum Mechanics (Bohr model) You should know about The energy of the n-th level for any atom: Solution Answer (A) decreased by a factor of 9 Reference https://en.wikipedia.org/wiki/Bohr_model

## GRE Physics GR 1777, Problem 015 Solution

GRE Physics GR 1777 Problem Solution 015. Electrodynamics (Speed of the light) Solution Answer (C)

## GRE Physics GR 1777, Problem 046 Solution

GRE Physics GR 1777 Problem Solution 046. Classical Mechanics (Hooke’s law) You should know about Hooke’s law The potential energy stored in a spring Solution Extension The same external force is applied to both springs,   Stored Potential Energy Answer (A) References https://en.wikipedia.org/wiki/Hooke%27s_law

## GRE Physics GR 1777, Problem 006 Solution

GRE Physics GR 1777 Problem Solution 006. Electromagnetism (Electromagnetic Waves) The problem asks you to determine The direction of the magnetic field of a plane electromagnetic wave. The problem gives The electric field. It is given by You should know about Property of the electromagnetic waves: The oscillations of electric and magnetic fields are perpendicular…

## GRE Physics GR 1777, Problem 021 Solution

GRE Physics GR 1777 Problem Solution 021. Electrodynamics (Cyclotron) Solution The cyclotron frequency is the frequency of a charged particle moving perpendicular to the direction of a constant magnetic field B. Since the motion of a charged particle in the cyclotron is circular (because of a uniform magnetic field), we can calculate the cyclotron frequency…

## GRE Physics GR 1777, Problem 020 Solution

GRE Physics GR 1777 Problem Solution 020. Electrodynamics (Magnetic field) Solution The magnitude of the magnetic field can be obtained from the Biot-Savart law. where is the radius of the loop and is the current. In this problem, the radius of the circular loop is , the magnitude of the magnetic field at the center…

## GRE Physics GR 1777, Problem 019 Solution

GRE Physics GR 1777 Problem Solution 019. Classical Mechanics (Work-Energy Principle) Solution From the work-energy theorem,   Since the work done by the box is and the change of the kinetic energy is   Therefore, The force is Answer (C) 3N Reference https://en.wikipedia.org/wiki/Work_(physics)#Work–energy_principle

## GRE Physics GR 1777, Problem 018 Solution

GRE Physics GR 1777 Problem Solution 018. Classical Mechanics (Angular Momentum) Solution Angular momentum in a circular motion is where is angular momentum, is the mass of the satellite, is the velocity, and is the orbital radius. In this problem, two satellites are identical. So the mass of the satellite is equal. The orbital radius…

## GRE GR 1777, Problem 017 Solution

GRE Physics GR 1777 Problem Solution 017. Classical Mechanics (Stellar Dynamics) Solution In Keplar’s Thrid law, the square of the orbital period of a planet is proportional to the cube of the semi-major axis of its orbit. where is the orbital period, and is the semi-major axis of the planet. For system 1 the radius…

## GRE Physics GR 1777, Problem 016 Solution

GRE Physics GR 1777 Problem Solution 016. Optics (Electromagnetics) This problem asks for the application of Fermat’s principle of ray optics to other optics laws. Solution This principle shows the path of the light, so it can also be used to explain reflection and refraction of the light. So we can derive Snell’s law and…