| The total resistance, Rₜ, in a series circuit is the sum of individual resistances:Rₜ = R₁ + R₂ + R₃ + … | Resistors in Series |
| How do you calculate the total resistance for resistors in series? | You add the resistances of all resistors together: Rₜ = R₁ + R₂ + R₃ + … |
| The total resistance, Rₜ, in a parallel circuit is given by the formula:1/Rₜ = 1/R₁ + 1/R₂ + 1/R₃ + … | Resistors in Parallel |
| How do you calculate the total resistance for resistors in parallel? | Use the formula: 1/Rₜ = 1/R₁ + 1/R₂ + 1/R₃ + … and take the reciprocal to find Rₜ. |
| How do you calculate the total resistance in a circuit that combines series and parallel resistors? | First, calculate the total resistance for resistors in parallel, then add that value to the resistances of the resistors in series. |
| Find the total resistance for resistors in parallel: Resistors: 4Ω and 16Ω 1/Rₜ = 1/4 + 1/16 = 5/16 Rₜ = 3.2Ω | Example Calculation |
| Power is the rate of energy transfer and can be calculated using: P = E/t, where E is the energy transferred and t is the time. | Power (P) |
| How do you calculate power if you know the energy transferred and the time? | Use the formula P = E/t. |
| Power can also be calculated using electrical formulas: P = VI P = V²/R P = I²R | Power Formulas |
| What are the different formulas to calculate power in a circuit? | P = VI
P = V²/R
P = I²R |
| How do you calculate energy transferred if you know the power and time? | Use the formula E = Pt. |
| A lamp has a power of 60 W and is connected to a 240 V power source. How much energy is transferred in 2 minutes? | Convert time to seconds: 2 minutes = 120 seconds
Use the formula E = Pt:
E = 60 × 120 = 7200 J |
| A lamp with a power of 60 W is connected to a 240 V power source. Find the current. | Use the formula I = P/V:
I = 60/240 = 0.25 A |
| In a series circuit, the current is the same everywhere in the circuit. | Series Circuit (Current) |
| What is true about the current in a series circuit? | The current is the same everywhere in the circuit. |
| In a series circuit, the battery p.d (potential difference) is shared across all elements, so the total sum of voltages equals the supply p.d. | Series Circuit (Voltage) |
| How is voltage shared in a series circuit? | The total sum of voltages across all elements equals the supply p.d. |
| In a parallel circuit, the sum of the currents in each parallel branch is equal to the total current of the circuit. | Parallel Circuit (Current) |
| How is current distributed in a parallel circuit? | The sum of the currents in each branch equals the total current. |
| In a parallel circuit, the potential difference across each branch is the same. | Parallel Circuit (Voltage) |
| How is voltage distributed in a parallel circuit? | The voltage across each branch is the same. |
| When cells are connected in series, the total voltage is the sum of the voltages of the individual cells:V_total = V₁ + V₂ + V₃ + ... | Series Configuration of Cells |
| What is the total voltage when cells are connected in series? | The total voltage is the sum of the individual cell voltages:
V_total = V₁ + V₂ + V₃ + ... |
| When identical cells are connected in parallel, the total voltage is equal to the voltage of one cell, as the current is split equally across branches. | Parallel Configuration of Cells |
| What is the total voltage when identical cells are connected in parallel? | The total voltage is equal to the voltage of one cell. V_total = V₁ = V₂ = V₃ = ... |
| In DC circuits, charge and energy are always conserved. | Conservation in DC Circuits |
| What is conserved in DC circuits? | Charge and energy are always conserved. |
| Kirchhoff’s First Law states that the total current flowing into a junction is equal to the current flowing out of that junction, indicating that no charge is lost at any point in the circuit. | Kirchhoff’s First Law |
| What does Kirchhoff’s First Law state? | The total current flowing into a junction is equal to the current flowing out of that junction, showing that no charge is lost. |
| Kirchhoff’s Second Law states that the sum of all the voltages in a series circuit is equal to the battery voltage, indicating that no energy is lost at any point in the circuit. | Kirchhoff’s Second Law |
| What does Kirchhoff’s Second Law indicate? | The sum of all voltages in a series circuit is equal to the battery voltage, showing that no energy is lost. |
| A potential divider is a circuit with several resistors in series connected across a voltage source, used to produce a required fraction of the source potential difference, which remains constant. | Potential Divider |
| What is the purpose of a potential divider? | To produce a required fraction of the source potential difference that remains constant. |
| A variable resistor can be used in a potential divider circuit to supply a variable potential difference by adjusting the resistance, which in turn affects the output voltage. | Variable Resistor |
| How does increasing the resistance across R₁ in a potential divider affect the output p.d.? | Increasing the resistance across R₁ will decrease the output p.d. because the circuit current decreases (V = IR). |
| A thermistor is a type of resistor whose resistance changes significantly with temperature, and can be used in a potential divider to create a temperature sensor. | Thermistor |
| A light dependent resistor is a resistor whose resistance decreases as light intensity increases, making it useful in potential dividers for light sensing applications. | Light Dependent Resistor (LDR) |
| What happens to the resistance of an LDR as light intensity increases? | The resistance of an LDR decreases as light intensity increases. |
| A sensor is a device that detects and responds to changes in the environment, triggering certain events based on the measured conditions. | Sensor |
| How can a light dependent resistor (LDR) be used in a circuit to trigger an event? | If the light intensity falls, the resistance across R₁ will increase, causing the circuit current to decrease, which leads to a decrease in the output potential difference (p.d). This can trigger an event such as turning off a light. |
| A threshold voltage is the minimum voltage level required to trigger a particular event, such as switching on a device like a light bulb. | Threshold Voltage |
| What happens to the output p.d when the LDR and resistor positions are switched in the circuit? | If the LDR and resistor positions are switched, the output p.d would increase as the light intensity decreases, potentially triggering an event such as turning on a light bulb. |
| Circuit current is the flow of electric charge in a circuit, which can change based on the resistance and voltage within the circuit. | Circuit Current |
