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CURRENT -VOLTAGE GRAPHS

CURRENT -VOLTAGE GRAPHS. Clicking on me will move you to the next page. BUTTONS. Clicking on me will take you to a list of equations, clicking on me again will take you back to the previous page. Click us;.

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CURRENT -VOLTAGE GRAPHS

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  1. CURRENT-VOLTAGE GRAPHS Clicking on me will move you to the next page. BUTTONS Clicking on me will take you to a list of equations, clicking on me again will take you back to the previous page. . Click us; Clicking on me will allow you to hear some information on the topic. Clicking on me again will stop the sound. Clicking on me will move you back a page. Clicking on me will reveal some information. Clicking on me will reveal an answer. TOPICS Jump to … Jump to … Clicking on me will bring you back to this page. Jump to… … the measuring circuit (3 pages). Jump to … Jump to … … resistor graph. Jump to … … measuring resistance from a graph. Clicking on me will take you to SI multipliers table. Clicking on me again will take you back to the page you were on previously. … explaining the graph(2 pages). …practice questions (2 pages). …exam question (3 pages).

  2. THE MEASURING CIRCUIT Variable D.C. Supply. 12V D.C. Supply. _ _ + + V V Ammeter in the flow – in series Ammeter in the flow – in series Variable resistor Circuit 1 Circuit 2 Component Component A A Voltmeter in parallel Voltmeter in parallel

  3. MEASURING CIRCUIT 1 V (volt) I (amp) 1 00 0 20.09 12 V D.C. supply 40.18 6 8 10 12 0.27 0.36 0.46 0.55 The Graph _ + Variable resistor 1 + A - The component 22 resistor Ammeter in the flow 6 4 8 2 10 0 12 - V + + V - Voltmeter in parallel

  4. MEASURING CIRCUIT 2 V (volt) I (amp) 1 0 00 Multimeter as an ammeter in series. 20.09 40.18 The Graph _ + 6 8 10 12 0.27 0.36 0.46 0.55 Multimeter used as a Voltmeter in parallel across the resistor.

  5. RESISTOR GRAPH 22  Resistor SMALLER resistance steeper line. I (current) 0.6 I (amp) V (volt) 22  0.5 2 0.09 0.4 Resistor 2 The pattern 4 0.18 6 0.27 0.3 47  BIGGER resistance line shallower 8 0.36 0.2 Resistor 1 10 0.46 0.1 12 0.55 -V (negative voltage) V (Voltage) 8 12 6 4 10 2 47  Resistor I (amp) V (volt) 2 0.04 4 0.09 6 0.13 - I (negative current) 8 0.17 10 0.21 A resistor (at a constant temperature) shows a straight line graph. The smaller the resistance the steeper is the graph. 12 0.24

  6. RESISTANCE FROM THE GRAPH Click on the button to find out how to: 58mA 56 52 48 44 Calculate Resistance Read the current Read the voltage 41mA 10.4 V 9.6 10.4 10.8 11.2 R = V = 7 V = 7V = 121 I58 mA 58 x 10-3 A R = V = 5 V = 5V = 122 I41 mA 0.041A R = V = 10.4 V = 10.4V = 120 I87 mA 0.087A

  7. EXPLAINING THE GRAPH Measuring resistance R = V = 2V = 8 ohm, I 0.25 R = V = 4V = 8 ohm, I 0.5 R = V = 6V = 8 ohm, I 0.75 A straight line shows that the resistance is constant. I  V 0.75A The Pattern 2V  4V 0.25A  0.5A 0.5A triple 2V  6V 0.25A  0.75A Double We say that the current is proportional to the voltage. 0.25A triple 6V 4V double 2V

  8. EXPLAINING THE GRAPH Current and Resistance We say that the current is inversely proportional to the resistance. 2 ohm resistor 1 R I  6A X 2 X 3  2  3 4 ohm resistor 3A 6 ohm resistor 2A 12V

  9. PRACTICE QUESTION 1 This is a current voltage graph of 3 different resistors. Clock on the correct sentences. I (current) A B The resistance of B is bigger than C. The resistance of C is bigger than A. The resistance of A is bigger than B. C - V V (voltage) The resistance of resistor B is constant. -I A straight line shows a constant resistance. A large resistance has a steep line. A small resistance has a steep line.

  10. PRACTICE QUESTION 2 I (Current) Use the information in the current-voltage graph to explain why the resistance of resistor A is smaller that the resistance of resistor B. A B As the resistance increases the current decreases if the voltage is constant. The dotted lone shows the voltage at 3V. At 3 volts, resistor B only allows a small current to flow while resistor A allows a much bigger current to flow. So, as the current through is A is larger than the current through B for the same voltage, the resistance of A is less than the resistance of B. Bigger current V (Voltage) 3V Smaller current The current through resistor A is 0.5 amp and the current through B is 0.1 amp at a voltage of 3 volts. Calculate the resistance of resistor A and resistor B. Resistor A: R = VI = 3 V 0.5A = 6 ohm Resistor B: R = VI = 3 V 0.1 A = 30 ohm

  11. EXAM QUESTION 1 Try to answer these exam questions. Once you’ve had a go, click on the button to see the answer the examiner was looking for; WJEC Physics P2 Jun. 2013 (Found.) Q.2 The current is the same in all parts of a series circuit. 3.0

  12. x

  13. (b) (i) Use the appropriate equation to calculate the the resistance of the resirtor for a voltage of 9 volts. Resistance = voltage equation current = 9V numbers 3 A = 3 ohm answer + unit Remember the order of calculations in Physics.

  14. EXAM QUESTION 2 Repeat the experiment and if the results are similar then the data is repeatable. As the length doubles the current halves. So for the same voltage , as the current halves the resistance doubles. WJEC Physics P2 May 2015 (Higher) Q.4

  15. EQUATIONS higher higher Open the file “Maths for Physics” for more about the use of mathematics in Physics.

  16. SI MULTIPLIERS k - kilo p - pico n - nano M - mega G - giga  - micro m - milli T - tera You only see the letter of the prefix on an exam paper, NOT the name. On a Foundation paper only milli, kilo a mega are used.

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