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If a bulb has a current of 20mA and voltage of 5V, and the current cost of electricity is £3 for a kW/hour. How much money would you spend to power the bulb for 8 hours? Are these good estimates for the current, voltage and cost of electricity?

Well we know that the power of the bulb is given by P = IV. Therefore the power = (20 x 10 -3 Coulomb per second) * (5 Joules per Coulomb) = 100 x 10 -3 Joules per second = 0.1 W. So the bulb uses 0.1 Joules...
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Answered by Anuradha V. • Physics tutor
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The normal price of the pair of shoes is £28. In a sale the price is reduced by 35%. What is the new price of the shoes?

If you take £28, what is 10% of 28? 2.8 So what is 30% of 28? You would do 2.8 x 3... which is? 8.4 And what is 5% of 28? You would half 2.8...so 1.4 Now add together 30% of 28 and 5% of 28... this gives 9.8...
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Answered by Seyta D. • Maths tutor
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Describe transport of materials by a river system

Salts and minerals are dissolved into the river water and thus travel in solution. Insoluble materal such as clay floats giving the river water a darker murky appearance as it travels in suspension. larger r...
JC
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What is the difference between the two main schools of thought on enzyme function?

The first of the two major theories are Lock and Key mechanism, which describes the perfect design of the enzyme active site to that of its substrate so that they can immediately interact on contact without ...
JC
Answered by Jonathan C. • Biology tutor
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How does heart muscle contract rhythmically in unison?

The heart is composed of a specialied muscle type called cardiac muscle. This has unique properties such that each muscle cell is connected together by gap junctions in their cell membranes (electrical synap...
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Answered by Jonathan C. • Biology tutor
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