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Charge, potential difference, energy and current

Charge, potential difference, energy and current. What does it mean if something is described as charged? the object has a net positive or negative charge due to electrons being taken away or given to the object (2 marks)

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Charge, potential difference, energy and current

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  1. Charge, potential difference, energy and current

  2. What does it mean if something is described as charged? the object has a net positive or negative charge due to electrons being taken away or given to the object (2 marks) • List 3 ways that static electricity is used in industry? Any three from: Electrostatic precipitator (smoke scrubbers in chimneys). Photocopiers. Printers. Powder coating/spraying. (3 marks) • For one of the above examples, describe how the process works. ……………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………….(4 marks) • What is the equation that links charge, current and time? Q = It ...................................................(1mark) • What is the equation that links charge, potential difference and energy? E = QV................................(1 mark) • How much charge flows when a current of 2A flows for 30 seconds? ..............................60C........................(1mark) • What current flows if a charge of 300C flows for 3minutes? ……………………1.7A....................................(1 mark) • What current flows if a charge of 270C flows for 106seconds? …………………2.5A…………………………………….(1 mark) • A p.d. of 12V is applied across a resistor. 250C of charge passes. How much energy was dissipated by the resistor ? …...............................3000J.........................................(1 mark) • A current of 0.12A flows through a resistor which has a resistance of 150 Ohms, 300C of charge passes. How much energy was dissipated by the resistor? V = IR V = 18..18x300 = 5400J.............................(2 marks) • A light bulb releases 230J of energy when connected to a 11V battery. How much charge flowed in the circuit? …………………20.9C………………………………….……(1 mark)

  3. The diagram shows a charged thundercloud. (a) Why does the tree below the thundercloud become positively charged? electrons / negative charges are Repelled (1 mark) (b) The base of the cloud has a negative charge of 18 coulombs. The potential difference between the base of the cloud and the ground is 1 200 000 kilovolts. (i) Write down the equation that links charge, energy transferred and potential difference. energy (transferred) = potential difference × charge (accept E = V × Q, accept W = V × Q) (1 mark)

  4. (ii) Calculate the maximum energy that could be transferred to the ground by a lightning strike. Show clearly how you work out your answer. ......E = VQ = 1200000 x 18 = 21600000000.......... Maximum energy transferred =21 600 000 000 or 2.16 × 1010 joules (2 marks) (c) A lightning conductor is usually attached to tall buildings. This reduces the risk of damage by a lightning strike. Explain why the lightning conductor is made of copper. copper is a good (electrical) conductor or copper has a low Resistance (1 mark) ......................................................................................................... provides path for electrons / electricity / lightning to earth / ground / metal plate (1 mark)

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