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Resistors Copy the graph of current – potential for a resistor (figure 3 p. 155) and label it. Define what an ohmic conductor is, how does resistance vary with the direction of current? Answer Qs 1 and 2 p. 155 in full in your book. More Current-Potential Graphs p. 156-157 Draw how the current and potential difference varies through a filament bulb (Fig 1). Use the information to describe why the graph is this shape. Use R = V/I and the graph to answer question a. Draw how the current and potential difference varies through a diode (Fig 2). Use the information to describe why the graph is this shape. Answer question b Draw how the current and potential difference varies through a Thermistor and LDR (Figs 4 & 5). Use the information to describe why the graph is this shape. Answer Questions c & d Complete the summary questions on page 157 in full. LDRS and Thermistors – summary Questions 1. Complete the following using the key words: diode; filament lamp; resistor; and thermistor a) The resistance of a... decreases as its temperature increases. b) The resistance of a… depends on which way round it is connected in a circuit. c) The resistance of a… increases as the current through it increases. d) The resistance of a… does not depend on the current through it. 2. A thermistor connected in series with an ammeter and a 3V battery is shown a) At 15oC the current through the thermistor is 0.2A and the potential difference across it is 3V – calculate its resistance at this temperature b) State and explain what happens to the ammeter reading if the thermistor’s temperature is increased Answers 1. a) The resistance of a thermistor decreases as its temperature increases b) The resistance of a diode depends on which way round it is connected in a circuit c) The resistance of a filament lamp increases as the current through it increases d) The resistance of a resistor does not depend on the current through it 2. a) Resistance = 15Ω (V/I) b) The ammeter reading increases because the resistance of the thermistor decreases