circuits-p4

• What is the flow of charge in electricity called?


  The flow of charge is called current
• What does potential difference (PD) tell us?


  Potential difference tells us how much energy is transferred per coulomb of charge
• What is the equation for potential difference?


  The equation for potential difference is $V =$$\frac{E}{Q}$
• How is current measured in a circuit?


  Current is measured with an ammeter
• What does resistance do in a circuit?


  Resistance resists the flow of charge or current through components
• What is Ohm's Law?


  Ohm's Law states that voltage is equal to current times resistance
• How does the IV graph of a resistor differ from that of a bulb?


  A resistor has a straight line graph, while a bulb has a curved graph indicating changing resistance
• What does a straight line through the origin on an IV graph indicate?


  A straight line through the origin indicates constant resistance
• What is the unit for resistance?


  The unit for resistance is Ohms
• How can resistance be calculated from an IV graph?


  Resistance can be calculated using $R =$$\frac{V}{I}$
• What does a curved graph for a bulb indicate?


  A curved graph for a bulb indicates that the resistance is changing
• What is the relationship between potential difference (PD) and current (I) in a resistor?


  They are directly proportional.
• What does a straight line graph of PD versus current indicate about a resistor?


  It shows that the resistor has constant resistance.
• What happens to the graph if the battery is reversed?


  Negative values for both PD and current are obtained, but the line remains straight through the origin.
• What does the gradient of the PD versus current graph represent?


  The gradient represents the resistance of the resistor.
• What is the equation for resistance according to Ohm's Law?


  V = I × R
• How can you find the resistance of a component from an IV graph?


  By picking a point on the line and rearranging Ohm's Law to find R = V / I.
• What happens to the graph when a bulb is used instead of a resistor?


  The graph becomes curved, indicating changing resistance.
• Why does the resistance of metals change with increasing PD and current?


  Because the collisions between electrons and ions increase, causing more resistance.
• What is a thermistor?


  A thermistor is a component whose resistance decreases as temperature increases.
• What is the function of a diode in a circuit?


  A diode allows current to flow in only one direction.
• What is the difference between a diode and an LED?


  An LED emits light while functioning as a diode.
• How does the length of a metal wire affect its resistance?


  Resistance is directly proportional to the length of the wire.
• What are the rules for components in series circuits?


  • Total PD is shared among components.
  • Current is the same through all components.
  • Total resistance is the sum of individual resistances.
• If two resistors of 10 ohms each are connected in series with a 6V battery, what is the voltage across each resistor?


  3V across each resistor.
• What happens to the total resistance when resistors are added in parallel?


  The total resistance decreases.
• What is the potential difference across each branch in a parallel circuit?


  The potential difference is the same for every branch.
• If the total current flowing through a battery is 0.5A and 0.2A flows through one resistor in parallel, what is the current through the other resistor?


  0.3A flows through the other resistor.
• What is the function of a light-dependent resistor (LDR)?


  • Resistance decreases with increased light intensity.
  • Used in applications like street lamps.
• How is power calculated in electrical circuits?


  Power is calculated using P = V × I.
• If a microwave draws 800W of power from a mains voltage of 230V, what is the current it uses?


  1. 48A (rounded to 3.5A).