HDE Section 1: Potential difference and work done (Electric Circuits) Flashcards
Define voltage?
Voltage is a general term referring to the amount of energy transferred per amount of charge.
The potential difference of a component is the amount of ________ that the component transfers into other forms of _____, per coulomb of charge passing through.
The potential difference of a component is the amount of energy that the component transfers into other forms of energy, per coulomb of charge passing through.
Define the electromotive force
The electromotive force (e.m.f.) of a source is the amount of energy it supplies to one coulomb of charge.
The element of an electric kettle that takes a current of 12.5 A produces 540 kJ of thermal energy in 3 minutes.
How much charge passes through the element in these 3 minutes?
What is the potential difference across the ends of the element?
a) 2250C
b) 240V
A 12V pump for a fountain in a garden pond can pump water up to a height of 0.80m at a rate of 4.8 litres per minute. How much work does the pump do per minute when raising the water to a height of 0.80 m? (You may assume that one litre of water has a mass of 1 kg.)
If the pump is 75% efficient, how much charge passes through the pump motor in one minute?
What current does the motor take when operating under these conditions?
a) 38 Jmin^-1
b) 4.2 C
c) 70mA
Define power
Power is the rate of doing work. This could also be stated as the rate of energy transfer.
True or False
Resistivity is a property of a material.
True
Is resistance directly proportional to resistivity?
Yes
higher resistivity = higher resistance
Is resistance inversely proportional to length?
Yes
longer wire = higher resistance
Is resistance inversely proportional to area?
Yes
larger area = smaller resistance
A wire is made of a metal with a resistivity of 2.85 x 10-8 Ωm. The wire is 0.32 m long and has a radius of 1.0 x 10^-3 m. The mass of the wire is 2.71 g.
Calculate the resistance of the wire.
2.9 x 10^-3 Ω
