## Empty Sphere field and potential

An empty sphere is charged. (the inner and outer radii of the sphere are $R_0$ and $R$). Please find the empty sphere field and potential as functions of $R$. What… Click here to read more

This site was started back in 2008, and features, among others, a collection of physics homework exercises and tutorials for all levels of physics students (high school and college).

We hope our site will help you advance in your studies and make it easier to understand physics, hence the world that surrounds us!

All the contents of this site were written by Valentin Bogatu (Physics, PhD).

Please help us spread the word. This site is free (supported by advertising) and your help is necessary to keep us going. Thank you for your visit.

An empty sphere is charged. (the inner and outer radii of the sphere are $R_0$ and $R$). Please find the empty sphere field and potential as functions of $R$. What… Click here to read more

Lagrangian symmetry Let up consider a one dimensional, two particles system. The two particles have an attractive force between them of the type $F=-kr^2$. Use the general coordinates $X$ (the… Click here to read more

Car Tire Pressure Prior to a street venture you verify the tire pressure on every one of the 4 tires worn out on your auto. You discover each is at… Click here to read more

A cylindrical capacitor is made up from two concentric cylinders ($R$ and $2R$). Inside the 2R cylinder there is a dielectric from 2R to 1.5R of constant $k=3$. The charges… Click here to read more

You are given a swinging pendulum that has a length of $l=10 cm$. This pendulum oscillates with a small amplitude. The amplitude of this swinging pendulum is $A=1 cm$ (when… Click here to read more

The CD player The GaAs semiconductor gap is 1.43 eV, while the AlGaAs gap is bigger of 2.06 eV. Please find a) The characteristic wavelength of photon absorbed by the… Click here to read more

A room that has walls that absorb sound has an open window of dimensions 2 x 1 m. There is a loudspeaker outside this room situated at a distance of… Click here to read more

Potentiometer and Resistor The resolution of a potentiometer is 0.1 mm, its length is 50 mm and its diameter is 5 mm. Please find the total resistance if the wire… Click here to read more

The Phonograph Experiment James and John bought from a sale an old phonograph. The phonograph speed can be changed. They are trying to do a physics experiment. The phonograph has… Click here to read more

The transformer and rectifier For a transformer that has two identical windings, the voltage from its center to one side is 22.0 V. The rectifier is made with two identical… Click here to read more

Tritium and Deuterium Please find energy that is necessary to remove a neutron of tritium ($^3H$) to give a deuterium atom ($^2H$) and a neutron. The rest energy for: neutron… Click here to read more

Wire loops in an external magnetic field One wire loops that is having a current 0f 140 mA and a radius of 0.06 m. This loop is situated in a… Click here to read more

Magnetic Fields of Sun and Earth The magnetic moment of Earth is $8*10^{22} A/m^2$ which is a big value. Also the Magnetic moment of Sun is big, but the distance… Click here to read more

The Simple Pendulum You are given a pendulum that is made from a rod of length b having at its end two masses m and M. Mass M can move… Click here to read more

The STM Please find the tunneling probability for a STM (Scanning Tunneling Microscope), if the probe work function is 4.0 eV, the gap is 0.50 nm and the atom is… Click here to read more

Charged wires You are given two parallel wires, charged with the same charge in absolute value, one is positively and the other is negatively charged. a. Find the electric field… Click here to read more

The Otto Cycle You have a “standard” Otto cycle. At the start of the adiabatic compression $P=100 kPa$ and $T=25 C$. If the efficiency of this engine is $eta=0.48$ and… Click here to read more

The Ampere Balance The Ampere Balance is made up from 2 parallel horizontal wires. Wire T is above wire H. Wire T makes a balanced pendulum The upper wire segment… Click here to read more

Photomultiplier Light incident on a photomultiplier cathode has an intensity of $1.2 pW/cm^2$ and an wavelength of $\lambda=450 nm$. The cathode area for light is $0.2 cm^2$ and the photomultiplier has… Click here to read more

The 2N3904 Transistor The current amplification $\beta$ value of the 2N3904 transistor is given by the relation $\beta=1.4T(C)+195$. For a temperature of T=25 C the value of $\beta=230$ from the… Click here to read more