For people studying A-level Physics (OCR).
June 17, 2019
June 17, 2019
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Physics Revision: Energy, Power and Resistance
What is a battery?
Two or more cells connected in series
A high-power cell
Two or more cells connected in parallel
What is potential difference?
A measure of the current carried by electrons
A measure of the transfer of energy by charge carriers
A measure of the charge in a circuit
A.measure of the strength of a circuit
What is the unit of electromotive force (EMF)?
Potential difference across a component divided by the current in said component
Potential difference across a component multiplied by the current in said component.
Current in a component divided by potential difference across said component.
The difference between potential difference and current.
What is Ohm's law?
For a metallic conductor kept at constant temperature, the current in the wire is inversely proportional to the pd across its ends.
For a metallic conductor kept at constant temperature, the current in the wire is inversely proportional to the square of the pd across its ends.
For a metallic conductor kept at constant temperature, the current in the wire is equal to the pd across its ends.
For a metallic conductor kept at constant temperature, the current in the wire is directly proportional to the pd across its ends.
What does the IV characteristic of a filament lamp look like?
A quadratic curve
An S-shaped curve
A straight line through the origin
A straight line
Why are diodes so useful?
They have no resistance.
The amount of current in them is easy to control.
They do not overheat.
They only allow current in one direction.
(Resistance x length)/cross-sectional area
(Length x cross-sectional area)/resistance
(Resistance/cross-sectional area) x length
(Resistance x cross-sectional area)/length
What happens to a thermistor as temperature increases?
Resistance stays constant
What happens to an LDR as light intensity increases?
Resistance stays constant.
What is the equation for electrical power?
Potential difference x resistance
Potential difference x current
What is the equation for electrical energy?
Energy = voltage x current x resistance
Energy = Power x time
Energy = Power/time
Energy = mgh
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