2. A Falkirk High School presentation

3. Ohm’s Law For each of the questions, click the letter of the correct answer Click to start the test

4. When a resistor is connected to a 3 Volt battery, a current of 6 Amps flows through it. Calculate the size of the resistor. B C D A0.5 ohms 2 ohms 3 ohms 18 ohms 1 a V A

5. When a resistor is connected to a 3 Volt battery, a current of 6 Amps flows through it. Calculate the size of the resistor. First draw the triangle that links voltage, current and resistance the answer R I V Sorry you’re wrong, let me show you how to do it. the question Now write down what the question is asking you to calculate. (Resistance) R = Now cover up R with your finger And see what’s left in the triangle I V 6 3 = =0.5 ohm Now substitute the numbers into the equation and calculate the answer. Click here for the next question V I

6. When a resistor is connected to a 12 Volt battery, a current of 8 Amps flows through it. Calculate the size of the resistor. A B C D 98 ohms 4 ohms 1.5 ohms 0.66 ohms 1 b

7. When a resistor is connected to a 240 Volt supply, a current of 6 Amps flows through it. Calculate the size of the resistor. A B C D 40 ohms 20 ohms 10 ohms 0.025 ohms 1 c

8. When a resistor is connected to a 9 Volt battery, a current of 45 milliamps flows through it. Calculate the size of the resistor. A B C D 6 ohms 0.2 ohms 20 ohms 200 ohms 2 a

9. Before you can start a calculation, you must make sure all the measurements are in Standard Units. R I V This is the same sort of calculation as before but this time the current is in milliamps. To change milliamps to Amps, you must divide by 1000 So 45 milliamps =45/1000=0.045 A R = I V 0.045 9 ==200 ohms so Click here for the next question

10. When a resistor is connected to a 3 Volt battery, a current of 150 milliamps flows through it. Calculate the size of the resistor. A B C D 20 ohms 2 ohms 5 ohms 50 ohms 2 b

11. When a resistor is connected to a 1.5 Volt cell, a current of 150 milliamps flows through it. Calculate the size of the resistor. A B C D 0.1 ohms 100 ohms 1 ohms 10 ohms 2 c

12. Calculate the current that would flow through a 3 ohm resistor when it is connected to a 1.5 Volt cell. A B C D 2 A 4.5 A 0.5 1.5 A 3 a

13. Calculate the current that would flow through a 3 ohm resistor when it is connected to a 1.5 Volt cell. First draw the triangle that links voltage, current and resistance the answer R I V Sorry you’re wrong, let me show you how to do it. the question Now write down what the question is asking you to calculate. (Current) I = Now cover up I with your finger And see what’s left in the triangle R V 3 1.5 = =0.5 A Now substitute the numbers into the equation and calculate the answer. Click here for the next question V R

14. Calculate the current that would flow through a 100 ohm resistor when it is connected to a 20 Volt supply. A B C D 0.1 A 0.2 A 5 A 2000 A 3 b

15. Calculate the current that would flow through a 30 ohm resistor when it is connected to a 3 Volt battery. A B C D 90 A 10 A 1 A 0.1 A 3 c

16. Calculate the current that would flow through a 3 k  resistor when it is connected to a 6 Volt battery. A B C D 18 A 0.018 A 0.002 A 2 A 4 a

17. Before you can start a calculation, you must make sure all the measurements are in Standard Units. R I V This is the same sort of calculation as before but this time the resistance is in k . To change k  to , you must multiply by 1000 So 3 k  =3x1000= 3000  I = R V 3000 6 ==0.002 A so Click here for the next question

18. Calculate the current that would flow through a 6 k  resistor when it is connected to a 24 Volt battery. A B C D 0.004 A 0.04 A 0.4 A 4 A 4 b

19. Calculate the current that would flow through a 9 k  resistor when it is connected to a 9 Volt battery. A B C D 1 A 0.1 A 0.01 A 0.001 A 4 c

20. Calculate the voltage over a 6  resistor if a current of 12 A flows through it. A B C D 0.5 V 2 V 72 V 0.002 V 5 a

21. Calculate the voltage over a 6  resistor if a current of 12 A flows through it. First draw the triangle that links voltage, current and resistance the answer R I V Sorry you’re wrong, let me show you how to do it. the question Now write down what the question is asking you to calculate. (Voltage) V = Now cover up V with your finger And see what’s left in the triangle R x I==72 V Now substitute the numbers into the equation and calculate the answer. Click here for the next question 6 x 12 RI

22. Calculate the voltage over a 30  resistor if a current of 0.5 A flows through it. A B C D 60 V 15 V 0.0016 V 150 V 5 b

23. Calculate the voltage over a 2  resistor if a current of 5 A flows through it. A B C D 0.4 V 0.1 V 2.5 V 10 V 5 c

24. Calculate the current that would flow through a 60  resistor when it is connected to a 3 Volt battery. A B C D 0.05 mA 20 mA 50 mA 180 mA 6 a

25. Calculate your answer as before. R I V This is the same sort of calculation as before but this time the answer is in mA. To change A to m , you must multiply by 1000 0.05 A =0.05x1000=50 mA I = R V 60 3 ==0.05 A so Click here for the next question

26. Calculate the current that would flow through a 480  resistor when it is connected to a 12 Volt battery. A B C D 25 mA 40 mA 0.025 mA 0.04 mA 6 b

27. Calculate the current that would flow through a 1000  resistor when it is connected to a 250 Volt supply. A B C D 2.5 mA 25 mA 250 mA 4 mA 6 c

28. When a resistor is connected to a 120 V supply, the current through it is measured to be 0.02 A. Calculate the size of the resistor. A B C D 6000 k  600 k  60 k  6 k  7 a

29. Calculate your answer as before. R I V This is the same sort of calculation as before but this time the answer is in k . To change  to k , you must divide by 1000 6000  = 6000/1000= 6 k  R = I V 0.02 120 == 6000  so Click here for the next question

30. When a resistor is connected to a 9 V supply, the current through it is measured to be 0.09 A. Calculate the size of the resistor. A B C D 0.1 k  1 k  10 k  100 k  7 b

31. When a resistor is connected to a 3 V supply, the current through it is measured to be 0.0015 A. Calculate the size of the resistor. A B C D 2000 k  200 k  20 k  2 k  7 c

32. The picture shows a circuit used to determine the size of a resistor. Close-ups of the readings are shown. Calculate the size of the resistor. A B C D 1.9  3.3  0.3  3.7  8 a

33. Sorry, you’re WRONG! Maybe you’ve made a mistake in reading the meter scales. The Voltmeter reading is 2.5 V So the ammeter reading is 0.76 A To calculate the resistance, you use R = I V 0.76 2.5 == 3.3  On the ammeter, 0.7 would be here.7

34. The picture shows a circuit used to determine the size of a resistor. Close-ups of the readings are shown. Calculate the size of the resistor. A B C D 1.9  9.4  2.4  1.2  8 b

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36. The picture shows a circuit used to determine the size of a resistor. Close-ups of the readings are shown. Calculate the size of the resistor. A B C D 9.2  7.7  0.69  0.13  8 c

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38. A B C D 5  6  5000  0.2  9 a The picture shows a circuit used to determine the size of a resistor. Close-ups of the readings are shown. Calculate the size of the resistor.

39. Sorry you’re wrong. Maybe you didn’t notice that the ammeter was measuring in milliamps To change mA to Amps, divide by 1000 So 0.3 mA =0.3 / 1000= 0.0003 A Click here for the next question

40. A B C D 4.1  4640  4800  4100  9 b The picture shows a circuit used to determine the size of a resistor. Close-ups of the readings are shown. Calculate the size of the resistor.

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42. A B C D 8333  10000  10  8.3  9 c The picture shows a circuit used to determine the size of a resistor. Close-ups of the readings are shown. Calculate the size of the resistor.

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