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Questions and Answers
What is the unit of resistance?
What is the unit of resistance?
According to Ohm's Law, what happens to the current when resistance increases in a circuit?
According to Ohm's Law, what happens to the current when resistance increases in a circuit?
If the voltage applied across a conductor doubles, what happens to the current assuming resistance remains constant?
If the voltage applied across a conductor doubles, what happens to the current assuming resistance remains constant?
What happens to the current if the resistance in a circuit decreases?
What happens to the current if the resistance in a circuit decreases?
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In Ohm's Law formula V=IR, what does 'I' represent?
In Ohm's Law formula V=IR, what does 'I' represent?
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If you want to calculate resistance and you know the voltage is 12V and the current is 3A, what is the resistance?
If you want to calculate resistance and you know the voltage is 12V and the current is 3A, what is the resistance?
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What is the resistance of the automobile when 5.00 A flows through it with a voltage of 20.0 V applied?
What is the resistance of the automobile when 5.00 A flows through it with a voltage of 20.0 V applied?
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If a temperature change of 1500oC is applied to the tungsten filament, what would be the new resistance?
If a temperature change of 1500oC is applied to the tungsten filament, what would be the new resistance?
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If the voltage applied to the automobile remains at 12.0 V, what current would flow through it if the resistance halves?
If the voltage applied to the automobile remains at 12.0 V, what current would flow through it if the resistance halves?
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What happens to the resistance of an automobile if the temperature around it increases significantly?
What happens to the resistance of an automobile if the temperature around it increases significantly?
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If a resistance wire experiences a temperature change of 100oC, what is the percentage change in resistance?
If a resistance wire experiences a temperature change of 100oC, what is the percentage change in resistance?
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What is the unit of measurement for voltage?
What is the unit of measurement for voltage?
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Who is credited with the invention of the electrochemical cell, also known as the battery?
Who is credited with the invention of the electrochemical cell, also known as the battery?
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Which of the following represents the flow of charge within a conductor?
Which of the following represents the flow of charge within a conductor?
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Who is the French physicist and mathematician known for his contributions to electromagnetism?
Who is the French physicist and mathematician known for his contributions to electromagnetism?
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What level of current can be described as 'Painful' according to the text?
What level of current can be described as 'Painful' according to the text?
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Which component opposes the push from the voltage source?
Which component opposes the push from the voltage source?
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Study Notes
Voltage
- Voltage is the "pusher" of electric charge (electrons) that causes current to flow.
- Voltage sources include batteries, generators, and outlets.
- Symbol for voltage is V, and its unit is Volts (V).
- Alessandro Volta, an Italian physicist, invented the electrochemical cell (battery) in 1800.
Current
- Current is the flow of electric charge (electrons) within a conductor.
- Charge will only flow if there is a voltage source (potential difference).
- Symbol for current is I, and its unit is Amps (A).
- André Ampère, a French physicist, is one of the main discoverers of electromagnetism.
- The SI unit of measurement for electric current, the ampere, is named after him.
- Effects of current on a person:
- 0.001 A: Can be felt
- 0.005 A: Painful
- 0.010 A: Involuntary muscle spasms
- 0.015 A: Loss of muscle control
- 0.070 A: If through the heart, serious injury, likely fatal if it lasts more than 1 second
Resistance
- Resistance opposes the "push" from the voltage source.
- Resistance affects the speed of the current.
- Symbol for resistance is R, and its unit is Ohms (Ω).
- Georg Ohm, a German physicist, determined that there is a direct proportionality between the voltage applied across a conductor and the electric current.
- Ohm's Law states that Voltage (V) is equal to Current (I) multiplied by Resistance (R).
Ohm's Law and Relationships
- If voltage in a circuit increases, the current will increase (direct proportional relationship).
- If voltage in a circuit decreases, the current will decrease (direct proportional relationship).
- If resistance in a circuit increases, the current will decrease (inversely proportional relationship).
- If resistance in a circuit decreases, the current will increase (inversely proportional relationship).
Temperature Variation of Resistance
- The resistance of a material can change with temperature changes.
- The equation 𝛒=𝛒o(1+ 𝛂𝝙T) can be used to calculate the resistance at different temperatures.
Devices Measuring Currents and Voltages
- Measuring currents and voltages can alter the circuit.
- Devices used to measure currents and voltages must be carefully designed to minimize their impact on the circuit.
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Description
Learn the fundamentals of current, voltage, and resistance in electrical circuits. Explore the concept of voltage as the 'charge pusher' and its sources like batteries and generators. Understand the unit for voltage and its significance in everyday applications.
