Search our library of Physics questions

Top answers

Physics

All levels

How can I derive the energy of an electron using the electron in a box model?

The electron in a box model uses the idea that the energy of the electron and that of a standing wave in a box are analogous. So using your knowledge of standing waves you can derive an equation for th...

Answered by Lucile C. • Physics tutor

13325 Views

Find the magnitude of the force on an electron that is travelling with velocity 2 x 10^4 ms^(-1) in the x direction through a uniform magnetic field of strength 2T in the y direction.

This question tells us we only need to consider the magnitude of the force, and since the magnetic field and electron's velocity are perpendicular, we can simply use the equation

Answered by Sally H. • Physics tutor

17037 Views

What is viscosity?

Viscosity is a measure of a fluid's resistance to flow. It describes the internal friction of a moving fluid. A fluid with large viscosity resists motion because its molecular makeup give...

Answered by Juan N. • Physics tutor

6184 Views

Why does lowering the control rods in a nuclear reactor reduce the amount of energy released each second from the nuclear fuel?

The boron control rods absorb slow-moving neutrons (thermal neutrons), which means that there are less available neutrons in the reactor. Since nuclear fission requires a collison between a neutron and...

Answered by Luke C. • Physics tutor

14352 Views

A capacitor discharge circuit of time constant 45ms includes a capacitor and resistor. The capacitor has a capacitance of 18µF What is the resistance of the resistor?

This question is in one of the CIE Physics Pre-U sample papers, and if you know the definition of the time constant for a capacitor circuit (=RC), its very easy, however even if you didnt it canbe deri...

Answered by Sam C. • Physics tutor

5448 Views