Search our library of Physics A Level questions

Top answers

Physics

A Level

Explain why gas bubbles rise faster through magma as they start to expand. (3)

Any object in a liquid/substance will experience a force called upthrust. This force is not dependent on the weight of the object, rather the amount of volume it takes up within the substance. When the ob...

Answered by Gabrielle R. • Physics tutor

3368 Views

An electron is traveling at a velocity of 500m/s perpendicular to a uniform magnetic field. A force of magnitude 4.32 x10^(-16) N is acting on the electron, what is the magnetic flux density of the field?

F=BQv so B=F/Qv (Q is the charge of an electron, 1.6 x10^-19C) so B=4.32 x10^-16 / (1.6 x10^-19 x 500) = 5.4 T

Answered by Christian J. • Physics tutor

1328 Views

Why does the rate of change of potential difference between two capacitor plates decrease as the capacitor discharges?

Current, I, is related to voltage by Ohm's law, I=V/R. As the capacitor discharges, the current will decrease as less charge is "released" from the capacitor. From Ohm's law, w...

Answered by Francis T. • Physics tutor

7721 Views

By referencing the magnetic field and the alternating potential difference explain how a cyclotron produces a beam of high speed particles.

The difference in potential between the two Ds of a cyclotron accelerate the particles across the gap. The direction of potential difference switches every half cycle to keep the particles accelerating. T...

Answered by Gareth R. • Physics tutor

3841 Views

Why does light change direction when it hits a surface with a different refractive index?

The path upon which light propagates is determined by Fermat's Principle. This says that light will always travel along the path of least time. Now, we often think of the speed of light as a constant, but...

Answered by Ben G. • Physics tutor

1912 Views