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What is electromotive force and how is it different to potential difference?

The electromotive force or emf of a cell in a circuit is, for a start, not a force at all: it has the unit of volts. A good definition is ‘the power supplied by the cell per unit current through the cell’ or...
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Answered by Tom B. • Physics tutor
12983 Views

A 2 kW electric fire is switched on for 30 minutes. How many Units of electricity does it use?

Units of electricity are measured in kWh (kilowatt-hours). We have our power in kW (2 kW) We have our time in minutes (30 minutes) Looking at the units, we can see that: kW x minutes = kWminutes (kWm) and kW...
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Answered by Andrew W. • Physics tutor
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How long have you been studying physics?

I have been interested in physics my whole life, when I was 12 I made my own wind turbine out of a plastic bottle (along with a few other materials!). I took both GCSE and A level physics and just finished m...
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Answered by Nathan G. • Physics tutor
2928 Views

How can an object accelerate without changing speed?

Acceleration is defined as the rate of change of velocity. Since velocity is a vector quantity (it has both magnitude and direction) defined as speed in a particular direction, any change in either speed or ...
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Answered by Ellen P. • Physics tutor
87275 Views

How can the first order kinematic (SUVAT) equations be derived?

We start with the following two observations about an object undergoing constant acceleration. First, its acceleration is equal to the change in its velocity over time, hence, a=(v-u)/t. Rearranging gives th...
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Answered by Peter T. • Physics tutor
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