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Physics
A Level

What is EMF? How do we test for it?

Electromotive Force (EMF) is the measure of how much energy a source like a battery gives to the charges in a circuit. As with most things, this energy source is not 100% efficient, and has an associated ...

Answered by Kieran M. Physics tutor
2860 Views

Explain why a transformer only works with an alternating current and doesn't with a direct current.

A transformer is designed to step-up or step-down a voltage in a wire to make transferring electricity more efficient. To do this they contain two isolated coiled wires (of varied lengths depending on the...

Answered by Brendan W. Physics tutor
19078 Views

Define Newtons law of Gravitation (in words or an equation).

Newtons law of gravitation can be described as: The force experienced by a body proportional to the product of the two masses the interaction is between, the gravitational constant 6.67x10-11 ,...

Answered by Brendan W. Physics tutor
2911 Views

Derive an expression to show that for satellites in a circular orbit T^2 ∝ r^3 where T is the period of orbit and r is the radius of the orbit.

This question is concerned with balancing forces. First, we must consider what forces are acting on the satellites. What is stopping the satellite from shooting off into space and what is preventing it fr...

Answered by Charlie M. Physics tutor
8934 Views

Describe how emission spectra are formed and how they can be used to identify the elemental composition of a star.

Electrons are bound to a nucleus in quantised energy levels. As they gain and lose energy they transition between this energy levels by emitting photons. Emitted photons have energies equal to the change ...

Answered by George P. Physics tutor
2090 Views

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