electricity Flashcards
resistors, current, resistance, potenial difference and electrial charge
Q: What is current in physics?
A: Current is the flow of charge, typically electrons, through a conductor.
Q: How does current flow in a series circuit?
A: In a series circuit, the current is the same at all points and flows from positive to negative.
Q: What is the formula relating charge, current, and time?
Q=I×t
Where:
𝑄
Q is the charge in coulombs (C),
𝐼
I is the current in amperes (A),
𝑡
t is the time in seconds (s).
Q: What does potential difference (voltage) measure?
A: Potential difference measures the difference in energy carried by the current between two points in a circuit.
Q: What is the formula for potential difference (voltage)?
A: The formula is V = E/Q, where V is potential difference (voltage), E is energy transferred, and Q is charge.
Q: What is resistance?
A: Resistance is how easy or difficult it is for current to flow through a component, measured in ohms.
Q: What is the formula for resistance?
R=V/I
Where:
𝑅
R is the resistance in ohms (
Ω
Ω),
𝑉
V is the voltage (or potential difference) in volts (V),
𝐼
I is the current in amperes (A).
Q: How is resistance caused?
A: Resistance occurs when electrons moving through a conductor collide with ions in the metal, making it more difficult for current to flow.
Q: What happens when resistors are added in series?
A: When resistors are added in series, the total resistance increases.
Q: What happens when resistors are added in parallel?
When resistors are added in parallel, the total resistance decreases. Resistors in parallel create less resistance than the same resistance in series.
Q: How does adding more resistors affect current in a circuit?
A: Adding more resistors reduces the current. In a series circuit, the current decreases with each additional resistor, while in parallel, the current increases.
Q: What happens to the total resistance in a series circuit?
A: The total resistance in a series circuit is the sum of the individual resistances.
Q: What happens to the current in a series circuit?
A: In a series circuit, the current is the same at every point.
Q: What is potential difference in a parallel circuit?
A: In a parallel circuit, the potential difference across each component is the same.
Q: What is the definition of current?
A: Current is the rate at which electrons flow through a circuit.
Q: What type of current does a battery produce?
A: A battery produces direct current (DC), where the current flows in one direction.
Q: What is the difference between direct current (DC) and alternating current (AC)?
A: Direct current (DC) flows in one direction, while alternating current (AC) constantly changes direction, caused by most generators, and is used by mains electricity.
Q: What is the voltage and frequency of mains electricity in the UK?
A: Mains electricity in the UK has a voltage of around 230V and a frequency of 50Hz.
Q: What is a step-up transformer?
A: A step-up transformer increases the voltage in the circuit, which reduces current and minimizes energy loss in power lines.
Q: What is a step-down transformer?
A: A step-down transformer decreases the voltage in the circuit, which increases current.
Q: What does a transformer do to the power in a circuit?
A: A transformer does not change the power in the circuit; it changes the voltage and current, but the power remains the same.
Q: What is the formula for electrical power?
A: Power = Current × Voltage
Q: What is the purpose of the National Grid in the UK?
A: The National Grid connects power stations to factories and homes across the UK, ensuring electricity supply.
Q: How does a step-up transformer reduce energy loss in the National Grid?
A: A step-up transformer increases the voltage, which decreases the current, reducing energy loss due to resistance in the power lines.
