AQA GCSE Physics 25 Current Electricity

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AQA GCSE Physics 2-5Current Electricity

• GCSE Physics pages 170 to 183

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AQA GCSE Specification

• CURRENT ELECTRICITY
• 12.6 What does the current through an electrical
  circuit depend on?
• Using skills, knowledge and understanding of how
  science works
• to interpret and draw circuit diagrams using
  standard symbols.
• to apply the principles of basic electrical
  circuits to practical situations.
• Skills, knowledge and understanding of how
  science works set in the context of
• Current-potential difference graphs are used
  to show how the current through a component
  varies with the potential difference across it.
• The current through a resistor (at a constant
  temperature) is directly proportional to the
  potential difference across the resistor.
• Potential difference, current and resistance
  are related by the equation
• potential difference current resistance
• The current through a resistor (at a constant
  temperature) is directly proportional to the
  potential difference across the resistor.
• Potential difference, current and resistance
  are related by the equation
• potential difference current resistance
• The resistance of a component can be found by
  measuring the current through, and potential
  difference across, the component.
• The resistance of a filament lamp increases as
  the temperature of the filament increases.
• The current through a diode flows in one
  direction only. The diode has a very high
  resistance in the reverse direction.
• The resistance of a light-dependant resistor
  (LDR) decreases as light intensity increases.

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Electric circuitsNotes questions from pages 170
171

• For an electric circuit to work, what must be
  true?
• Copy Figure 2 on page 170.
• Copy and answer questions (a), (b) and (c) on
  pages 170 and 171. Include the diagrams with
  questions (b) and (c).
• Copy the Key Points on page 171.
• Answer the summary questions on page 171.

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Electric circuits ANSWERS

• In text questions
• So current passes through it and through the
  lamp.
• Two cells, a switch and a heater.
• No.

• Summary questions
• 1. Cell, switch, indicator, fuse.
• 2. (a) The diode arrow should be pointing to the
  right.
• (b) A variable resistor.

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ResistanceNotes questions from pages 172 173

• Copy Figure 1 on page 172 and explain the
  placement of the two meters.
• Explain what causes a conductor to have
  resistance.
• Copy the equation for resistance on page 172
  along with the units used and the symbolic
  version of the equation.
• Copy and answer question (a) on page 172.
• What is Ohms law?
• Sketch the current-potential difference graph of
  a wire and explain how this graph shows that the
  wire obeys Ohms law.
• Copy and answer question (b) on page 173.
• Copy the Key Points on page 173.
• Answer the summary questions on page 173.

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Resistance ANSWERS

• In text questions
• 8.0 O
• 10 O

• Summary questions
• 1. (a) The diagram should be the same as Figure 2
  on page 173 but it does not need to have the
  variable resistor.
• (b) 8.0 O
• 2. W 6.0O X 80V
• Y 2.0A Z 24O

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More current-potential difference graphs Notes
questions from pages 174 175

• Copy Figure 1 on page 174 and explain why the
  resistance of a filament lamp varies with
  potential difference.
• Copy Figure 2 on page 174 and explain how the
  resistance of a diode varies with potential
  difference.
• Copy and answer questions (a) and (b) on page
  174.
• Copy Figure 4 on page 175 and explain how the
  resistance of a thermistor varies with
  temperature.
• Copy Figure 5 on page 175 and explain how the
  resistance of a light dependent resistor varies
  with brightness.
• Copy and answer question (c) on page 175.
• Copy the Key Points on page 175.
• Answer the summary questions on page 175.

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More current-potential difference graphs ANSWERS

• In text questions
• (i) 5.0 O (ii) 10 O
• It decreases
• The resistance is constant.

• Summary questions
• (a) thermistor
• (b) diode
• (c) filament lamp
• (d) resistor
• 2. (a) 15 O
• (b) The ammeter reading increases because
  the resistance of the thermistor decreases.

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Series circuitsNotes questions from pages 176
177

• Copy and explain the two circuit rules for series
  circuits. Draw Figures 1 and 2 on page 176.
• Copy and answer questions (a) and (b) on page
  176.
• Explain what happens when cells are connected
  together in series.
• Copy Figure 4 on page 177 and explain what
  happens when resistors are connected in series.
• Copy and answer questions (c) and (d) on page
  177.
• Copy the Key Points on page 177.
• Answer the summary questions on page 177.

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Series circuits ANSWERS

• In text questions
• 0.12 A
• 0.4 V
• 1.1 V
• 5 O

• Summary questions
• (a) The same as
• (b) Less than
• 2. (a) (i) 12 O (ii) 3.0 V
• (b) 3V / 12O 0.25 A
• (c) P 0.5V Q 2.5V

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Parallel circuitsNotes questions from pages 178
179

• Draw a diagram to illustrate the rule about
  currents, stated on page 178, through parallel
  components.
• Copy Figure 2 on page 178 and explain the rule
  about potential difference in a parallel circuit.
• Copy a different version of the worked example on
  page 179. In your version show the calculations
  if the battery was 12V instead of 6V.
• Copy and answer questions (a) and (b) on pages
  178 and 179.
• Copy the Key Points on page 179.
• Answer the summary questions on page 179.

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Parallel circuits ANSWERS

• In text questions
• 0.30 A
• The 3O resistor

• Summary questions
• (a) Potential difference
• (b) current
• (a) R1 3A
• R2 2A
• R3 1A
• (b) 6A

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Circuits in control Notes questions from pages
180 181

• Answer questions 1 and 2 on page 181.

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Circuits in control ANSWERS

• A daytime fire alarm
• A greenhouse alarm if the sunlight is too strong
  or the temperature is too high.

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How Science Works ANSWERS

• minus 50oC to 150oC.
• It might work, but it would not be accurate.
• 0.1oC
• It cannot be relied on to be giving a more
  accurate temperature than 0.3oC above or below
  that recorded.
• The company could be biased.
• It had been independently calibrated.
• 37.45oC and 37.4oC
• The technician could have checked the temperature
  of the water with the two thermometers at the
  same time.
• No. The new thermometer had a range of minus 50oC
  to 150oC.
• No. Because they are all within the 0.3oC