Electricity and Circuits Flashcards
broad range of topics covered, such as charge, current, resistance, circuits, voltage, and practical experiments.
Q: What charge does a proton have?
A: A proton has a positive charge.
Q: What charge does a neutron have?
A: A neutron has zero charge (neutral).
Q: What charge does an electron have?
A: An electron has a negative charge.
Q: What is the relationship between protons and electrons in an atom?
A: Protons and electrons have equal and opposite charges.
Q: What is the charge of the nucleus of an atom?
A: The nucleus of an atom is positively charged.
Q: What is the composition of the nucleus of an atom?
A: The nucleus is composed of protons and neutrons.
Q: Where are electrons located in an atom?
A: Electrons move in a space surrounding the nucleus.
Q: What is a charged atom called?
A: A charged atom is called an ion.
Q: How does an uncharged atom become charged?
A: An uncharged atom becomes charged by transferring a proton to or from it.
Q: What is static electricity and why can it be dangerous?
A: Static electricity is the buildup of electric charge on a surface, and it can be dangerous if it leads to sparks, fires, or electrical damage.
Q: How can objects experience a force from an electric field?
A: Objects with electric charge experience a force from an electric field even if they are not touching.
Q: What is an electric field?
A: An electric field is the space around an electrical charge where it exerts a force on other charges.
Q: How is an electric field similar to a gravitational field?
A: An electric field surrounds a charge, similar to how a gravitational field surrounds a mass.
Q: How do the field lines behave in a positive electric field?
A: In a positive electric field, the field lines point outward.
Q: How do the field lines behave in a negative electric field?
A: In a negative electric field, the field lines point inward.
Q: What is measurement error?
A: Measurement error is the difference between the real value and the measured value.
Q: What is random error?
A: Random error causes measurements to be spread around the true value, and it can be reduced by taking repeated measurements and calculating the mean.
Q: What is current in physics?
A: Current is the flow of charge, typically electrons, through a conductor.
the charge carriers in electrical cricuits are electrons
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?
A: The formula is , where is charge, is current, and is time.
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 , where is potential difference (voltage), is energy transferred (in joules), and 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?
resistance (ohms) = voltage(V)/current(amps)
Q: How is resistance caused?
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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?
A: When resistors are added in parallel, the total resistance decreases.
resistors in parrallel create less reisstance than the same resistance in series (2 paths for the current)
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 and has a constant potential differnce (AC) constantly changes direction caused by most generators and is used by mains electricity and has an alternating potential diffrence.
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 x 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.
REQUIRED PRACTICAL 4
investigating the link between voltage and current for a fixed resistor a diode and filament lamp
Equipment List
Ammeter
Voltmeter
Variable resistor
Fixed resistor (between 100 Ω and 500 Ω)
Filament lamp
Diode
Voltage Supply
Wires
Set up the circuit as shown with the fixed resistor
Vary the voltage across the component by changing the resistance of the variable resistor, using a wide range of voltages (between 8-10 readings). Check the appropriate voltage reading on the voltmeter
For each voltage, record the value of the current from the ammeter 3 times and calculate the average current
Increase the voltage further in steps of 0.5 V and repeat steps 2 and 3
Make sure to switch off the circuit in between readings to prevent heating of the component and wires
Reverse the terminals of the power supply and take readings for the negative voltage (and therefore negative current)
Replace the fixed resistor with the filament lamp, then the diode, repeating the experiment for each
resistance in series
In series the total resistaance is added
the total resistance in series is the sum of the resistance of each component
R total = R(1)+R(2)+R(3)
^series circuits - resistance increases as more components are added
[100 ohms] + [45 ohms] + [28 ohms]
100+45+28 = total resistance
what happens to the reistance when components are in series
the reistance adds up
how do you calculate total resistance in series
add it up
what happens to resistance when the components are added in parallel
it goes down (reistance is always less than the lowest)
ohms law aka V=IR
the current through a conductor is directly proportional to the potential resistance (voltage) across it provided temp remains constant
makes more sense as R=v/i or pd(voltage)/current= resistance
large resistance means you need lots of volts to get a small current
formula for resistance
resistance(R) = potential difference(V)/ current (A)
what is resistance
how easy/difficult it is for current to flow - measured in ohms
it is also how many volts are needed per amp of current
what is current and pd in series circuits
current stays the same
pd is split/shared
(opposite to parallel)
what is current and pd in parallel circuits
current is split/shared
pd stays the same
(opposite to series)
what is the formula used to relate charging current
Q(charge) = I(current) x T(time)
effects of resistors
adding resitors reduces current
2 resistors in series have greater resistance than 1 alone
resistors in parallel create less reisstance than the same resistance in series (2 paths for the current)
electrical charge formula
current(amps)= charge(colombs)/time (seconds)
potential diffrence(voltage ) and its formula
symbol V (measured in volts )
a measure of the diffrenece in enegery carried by current ( moving electrons )
so we have to measure it at 2 diffrent points
the potential diffrence is the amount of energy tranferred (work done) for each coloumb of charge as it passes through a component
IN FORMULA
potential diffrence = energy transferred / charge
V=E/Q
light dependent reistor
a compondednt where the resistance varies with the light levels
thermistor
a type if reistor where the reistance varies with temprature
