Robotics/Electronics Review for the Final Exam

Transcription

1 Robotics/Electronics Review for the Final Exam Unit 1 Review. 1. The battery is 12V, R1 is 400 ohms, and the current through R1 is 20 ma. How many ohms is R2? ohms What is the voltage drop across R1? V What is the voltage drop between points A and B? V What is the current through point A? ma A B 2. The current through R1 is 25 ma, R2 is 250 ohms, and the voltage drop across R2 is 7.5V. How many volts is the battery? V What is the current through R2? ma What is the current through point A? ma How many ohms is R1? ohms A 3. This is a 30V battery. R1 is 100 ohms. There is a 7V drop across R2. The current through R3 is 40mA. R2 is ohms R3 is ohms The voltage drop across R1 is volts The voltage drop across R3 is volts 4. The current through R1 is 12 ma and the current through R2 is 24 ma. R1 is 300 ohms and R3 is 450 ohms. A How many volts is the battery? V What is the current through R3? ma What is the current through point A? ma How many ohms is R2? ohms

2 5. If we have a 9 volt battery and we want a 2.2 V voltage drop across the LED at 20 ma, what value should the resistor be? ohms 6. Suppose the voltage drop across the LED is 1.8V, the voltage drop across R1 is 2.1V, the voltage drop across R2 is 1.5V, and the current through the LED is 15mA. How many volts is the battery? V How many ohms is R1? How many ohms is R2? 7. To the right is a sketch of a multi-meter attached to a live circuit (one with a working battery attached). Select the true statement(s). a) If the dial is set correctly, it could be measuring the resistor s resistance. b) If the dial is set correctly, it could be measuring the current through the resistor. c) If the dial is set correctly, it could be measuring the voltage drop the resistor. d) None of the above. 8. To the right is a sketch of a multi-meter attached to a live circuit (one with a working battery attached). Select the true statement(s). a) If the dial is set correctly, it could be voltage drop between the two resistors. b) If the dial is set correctly, it could be measuring the current between the two resistors. c) If the dial is set correctly, it could be measuring the battery s voltage. d) None of the above. 9. With the multi-meter set to 20kΩ, R1 measures 1.2. The battery is 6V. What is the current through R1? ma

3 10. The figure to the right shows: a) a short circuit b) an open circuit c) a closed circuit with an LED and resistor in series d) a closed circuit that only contains a resistor. The LED is not part of the circuit. 11. Suppose the voltage drop across R1 is 4 volts. Select the TRUE statement(s). a) The battery must have more than 4 volts. b) The voltage drop across the LED might be around 2 or 3 volts. c) The voltage drop across the LED is zero. d) There is not enough information to select any of the above answers. 12. Each of the three resistors are 500 ohms. The battery is 9V. What is the voltage drop across the bottom resistor? What is the voltage drop across the middle resistor? What is the voltage drop across the top resistor? 13. The battery is 7.2V. The top resistor is 600 ohms and the bottom resistor is 400 ohms. What is the current through the top resistor? ma What is the current through the bottom resistor? ma 14. This circuit is a) a short circuit b) an open circuit c) a closed parallel circuit d) a closed series circuit

4 15. This circuit is a) a short circuit b) an open circuit c) a closed parallel circuit d) a closed series circuit 16. Select the true statement(s). If the voltage drop across R1 is greater than the voltage drop across R2 then a) R1 has a greater resistance than R2. b) R2 has a greater resistance than R1. c) The current through R1 is greater than the current through R2. d) The current through R2 is greater than the current through R1. Unit 2 Review. 17. The LED will blink on and off... a) with the LED being on about the same amount of time as it is off. b) with the LED being on about twice as long as it is off. c) with the LED being off about twice as long as it is on. 18. After line 1 is executed but before line 2 is finished, the voltage drop from pin 12 to the ground is approximately V pinmode( 12, OUTPUT ); digitalwrite( 12, HIGH ); delay( 800 ); digitalwrite( 12, LOW ); delay( 400 ); 19. After line 3 is executed but before line 4 is finished, the voltage drop from pin 12 to the ground is approximately V. 20. After the setup function has been executed, what is the value of x? int x = 70; x = 36; x = 47;

5 21. The user will see a) the LED go on for a second and then stay off. b) the LED go on and stay on. c) the LED blink on and off. pinmode( 3, OUTPUT ); digitalwrite( 3, LOW ); delay( 1000 ); digitalwrite( 3, HIGH ); 22. In the above circuit, if the resistor is 400 ohms and the voltage drop across the LED is 2V when the light is on, what is the current when the LED is on? ma 23. What is displayed? If more than 6 numbers are displayed then just write the first How many assignment statements are in the setup function? 25. What has been displayed after the loop function has been executed twice? 26. What has been displayed after the loop function has been executed twice? int k = 2; int h = 6; int g = 11; h = k; k = g; g = h; Serial.println( k ); Serial.println( h ); Serial.println( g ); int bob = 0; int ann = 0; bob = bob + 3; ann = 8; Serial.print( bob ); Serial.print( ", " ); Serial.print( ann ); int y = 2; y = y + 1; Serial.println( y ); y = y + 6;

6 27. Select the TRUE statement. a) The LED will blink on and off. b) The LED will always stay on but it alternates between very bright and less bright. c) The LED starts out bright and gradually gets dimmer and dimmer pinmode( 12, OUTPUT ); analogwrite( 12, 255 ); delay( 2000 ); analogwrite( 12, 100 ); delay( 2000 ); 28. While line 4 (in the above problem) is being executed, what is the voltage drop from pin 12 to ground? V (round to the nearest tenth) 29. Select the TRUE statement. a) The analogwrite function can be used with any digital pin. b) The analogwrite function only works with digital pins labelled with a tilde (~). c) The analogwrite function only works with analog pins. 30. Complete the code below so that the numbers 500, 480, 460, and so on are displayed in the Serial Monitor. There should be a three second delay between printing numbers. 31. Complete the code below so that the numbers 33, 37, 41 and so on are displayed in the Serial Monitor. There should be a half second delay between printing numbers. int x = Serial.println( x ); delay( ); int x = Serial.println( x ); delay( );

7 32. What is displayed? int x = 24; x = 8 + x / 4 + 4; Serial.println( x ); Unit 3 Review. Assume that there are two LED circuits. There are also two voltage divider circuits. 33. If g is 600 and h is 900, then a) Both LEDs are on. b) Both LEDs are off. c) The LED attached to pin 9 is on, the other is off. d) The LED attached to pin 9 is off, the other is on. 34. If g is 512 and h is 512, then a) Both LEDs are on. b) Both LEDs are off. c) The LED attached to pin 9 is on, the other is off. d) The LED attached to pin 9 is off, the other is on. int g; int h; pinmode( 9, OUTPUT ); pinmode( 10, OUTPUT ); g = analogread(3); h = analogread(4); if ( g <= 512 ) digitalwrite( 9, LOW ); else digitalwrite( 9, HIGH ); 35. Excluding the wires to the ground pins, based on this code, which digital pins have wires connected to them? Which analog pins have wires connected to them? if ( h > 512 ) digitalwrite( 10, HIGH ); else digitalwrite( 10, LOW ); 36. How many boolean expressions are in this code? 37. How many assignment statements are in this code?

8 38. Complete the code below so that the user can turn the LED on and off using the potentiometer. If the potentiometer is turned so that the voltage drop from analog pin 0 to ground about 1 volt or less, the LED should go off. Otherwise the LED should be on. Do not bother to include Serial.begin or Serial.println. Your loop function might not use all the lines that were provided. 39. If y has a value of 750, what is printed? 40. Assuming that y can have any value between 0 and 1023, which letter is most likely to be printed? 41. Assuming that y can have any value between 0 and 1023, which letter is least likely to be printed? int y; Serial.begin(9600 ); y = analogread(3); if ( y > 700 ) Serial.println( "A" ); else if ( y > 900 ) Serial.println( "B" ); else if ( y > 500 ) Serial.println( "C" ); else Serial.println( "D" );

9 Use this code and schematic in answering question 42. For the purposes of these questions, use these resistance values for the photo-resistor: 10 kω very dark 7.5 kω dark 5 kω moderate 2.5 kω bright 1 kω very bright int n; Serial.begin(9600); n = analogread( 5 ); Serial.println( n ); delay(500); 42. In this problem you must use the rounded answer from one part in solving the next part. If n has a value of 716 and R2 is 17.5 kω, then the voltage drop across the photo-resistor is V (round to the nearest tenth) the current through R2 is ma (round to the nearest tenth) the photo-resistor has a resistance of ohms (round to the nearest whole number). the lighting around the photo-resistor is : a) very dark b) dark d) bright c) moderate e) very bright R1 is a 10 kω potentiometer. The resistance from the middle pin (which is connected to a wire that goes to analog pin 5) to ground is 2.5 kω. Use this code and schematic in answering questions 43, 44, and 45. int n; Serial.begin(9600); n = analogread( 5 ); Serial.println( n ); delay(500); 43. You must use the rounded answer from one part in solving the next part. What is the value of n? What is current through R1? ma (round to the nearest tenth) 44. If the knob on the potentiometer is turned all the way to the left or right, then n will either be or. (It depends on how the potentiometer is oriented.) 45. As you turn the potentiometer knob, the current through the potentiometer will a) increase or decrease, depending on how you turn the knob. b) stay the same.

10 Use this code and schematic in answering questions 46 to 48 For the purposes of these questions, use these resistance values for the photo-resistor: 10 kω very dark 7.5 kω dark 5 kω moderate 2.5 kω bright 1 kω very bright int v; v = analogread( 3 ); if ( v <= 511 ) Serial.println( "A" ); else Serial.println( "B" ); 4.7 kω 46. Select the TRUE statement(s). a) If it is very dark then A will be printed. b) If it is very dark then B will be printed. c) If it is very bright then A will be printed. d) If it is very bright then B will be printed. e) There is not enough information to select any of the above choices. 47. If v equals 511, what is the current through the circuit? ma (round to nearest tenth) 48. As it gets darker, the current through the circuit will a) decrease. b) increase. c) There is not enough information to determine if the current increases or decreases. 49. The 5 in line 1 refers to a) 5 volts b) analog pin 5 c) digital pin 5 d) analog or digital pin 5 (could be either one) 50. If z has a value of 982, that indicates a voltage of V (round to the nearest tenth) 51. If z is around 900 then a) we know that it is dark or very dark out. b) we know that it is bright or very bright out. c) we don t have enough information to determine how bright or dark it is. 52. If the fixed resistor is 5 kω and it is bright around the photoresistor, what is the value of z? 1 Assume that this is code for a voltage divider circuit where z indicates the voltage drop across a photo-resistor. int z; Serial.begin(9600); z = analogread( 5 ); Serial.println( z ); delay(500);

11 53. On the left is a voltage divider circuit and a resistor. On the right are two LED circuits. Complete the code below so that if the voltage drop across the photo-resistor is: - more than 4 volts then both LEDs are off. - less than 1 volt then both LEDs are on. - otherwise then the top LED is on and the bottom LED is off. Do not bother to include Serial.begin or Serial.println. Your loop function might not use all the lines that were provided. Unit 4 Review. 54. What has been displayed after the loop function has been executed twice? 55. Name all the local variables. If there are none, write NONE. unsigned long a = millis(); Serial.println( a ); delay( 500 ); unsigned long b = millis(); Serial.println( b );

12 56. Digital pin 4 is not connected to anything and is floating. Select the TRUE statement. a) It will always display A. b) It will always display B. c) It will always display C. d) It will randomly display either A or B but never C. e) It will randomly display A, B, or C. f) It will randomly display either A or C but never B. The figure to the right shows the voltage drop across a button as a function of time. 5V Detected Voltage int x = digitalread( 4 ); if ( x == 1 ) Serial.println( "A" ); else if ( x == 2 ) Serial.println( "B" ); else Serial.println( "C" ); The various times (t 1, t 2, etc.) represent specific times at which the digitalread function is called. 0 t 1 t 2 t 3 t 4 t 5 t 6 t 7 t 8 t 9 t 10 time 57) Name all the global variables in this code. If there are none, write NONE. 58) At time t 1, what is x equal to? 59) Assuming that digitalread is first called at t 1, what is the value of count just after t 10? 60) Assuming that digitalread is first called at t 1, what is the value of count just after t 10? 61) How many times will the letter G be printed? int count = 0; int x = digitalread( 8 ); if ( x == HIGH ) count = count + 1; int count = 0; int previousx = LOW; int x = digitalread( 8 ); if ( x == LOW && previousx == HIGH ) count = count + 1; previousx = x; int previousx = LOW; int x = digitalread( 8 ); if ( x == LOW && previousx == HIGH ) Serial.println( "G" );

13 62. Use the figure on the right. Select the TRUE statement. a) If the button is pressed, there will be a short circuit. If the button is not pressed, then there is no short circuit. b) There is always a short circuit. It does not matter if the button is pressed or not. c) There is never a short circuit. When the button is pressed, the LED goes on. If the button is not pressed then the LED is off. d) The LED is always on. e) The LED is always off. 63. What has been displayed after the loop function has been executed twice? 64. How many milliseconds does it take for the loop function to be executed twice? int num = 0; f2( num ); num = num + 3; f1( num ); num = num + 4; void f1( int n ){ Serial.println( n ); delay( 100 ); void f2( int n ){ Serial.println( n ); delay( 200 ); 65. In which line(s), is the fx function called? 66. What is displayed after the loop function has been executed twice? 67. How many milliseconds does it take to execute the loop function twice? int a = 20; Serial.begin( 9500 ); a = a 1; fx( a ); a = a + 3; fx( a ); delay( 500 ); void fx( int k ){ Serial.println( k ); delay( 200 );

14 68. There are two LED circuits connected to pins 7 and 8. There is also a potentiometer connected to analog pin 3. As the knob of the potentiometer is turned, both LEDs are on or both LEDs are off. It should be equally easy to turn both LEDs on as turn them off. Finish the code in the loop function by correctly call the set_leds function. pinmode( 7, OUTPUT ); pinmode( 8, OUTPUT ); int x = analogread( 3 ); void set_leds( int x ){ if ( x == 2 ){ digitalwrite( 7, HIGH ); digitalwrite( 8, HIGH ); else { digitalwrite( 7, LOW ); digitalwrite( 8, LOW ); 69. What has been displayed after the loop function has been executed twice? int w = 15; Serial.begin( 9500 ); int x = 11; Serial.print( "x " ); Serial.println( x ); Serial.println( w ); x = x + 3; w = w + 4;

15 70. What is displayed after the loop function has been executed twice? 71. How many milliseconds does it take to execute the loop function twice? 72. What parameters does the fx function have? If there are none, write NONE. int x = 400; Serial.begin( 9500 ); x = x + 10; fx( 300, x ); fx( x, 1000 ); void fx( int a, int b ){ Serial.println( a ); delay( b ); 73. There is a button circuit connected to pin 8 and an LED circuit connected to pin 2. Complete the code so that when the program starts, the LED is on. When the button is clicked twice, the LED goes off and stays off until the button has been clicked a total of 6 times. Then it goes back on and stays on.

16 74. There is a working LED circuit connected to pin 5. Complete the loop function so that the fun function is called twice; once so that the LED turns on followed by a two second delay and once so that LED turns off followed by a one second delay. You may not need to use all the lines. pinmode( 5, OUTPUT ); void fun( int x, int y ){ digitalwrite( 5, y ); delay( x ); Unit 5 Review. 75. What is displayed? int a = func( 3, 5 ); Serial.println( a ); a = func( 5, 3 ); Serial.println( a ); int func( int x, int y ){ int z = 2*x + y; return z; 76. What is displayed? int a = fx(); int b = fx(); Serial.println( a+b ); int fx(){ return 22; return 5; return 100;

17 This is a robot with an ultra-sonic sensor. 77. Complete the code as follows: - Call the distance function. - If something is detected between 5 and 10 inches, go forward as fast as possible. - If something is detected closer than 5 inches then call the reverse function with a value of If something is detected farther than 10 inches, turn for 500 milliseconds. All the necessary variable declarations all the necessary code void forward( int a ) { code that makes it go forward, a is between 0 and 255 void reverse( int b ) { code that makes it go forward, b is between 0 and 255 void turn( int c ){ code that makes it turn, c is the number of milliseconds it should turn int distance() { code identical to what we used in class for the ultra-sonic sensor except that a 50 millisecond delay has been added to prevent overlapping echoes. 78. Assume that this function would make the robot go forward in a straight line. If the 255 in lines 2 and 4 were changed to 150 then the function would a) cause the robot to turn. b) cause the robot to stop moving. c) cause the robot to go backwards. d) cause the robot to continue going forward but slower void forward() { digitalwrite(dira, HIGH); analogwrite(pwma, 255); digitalwrite(dirb, HIGH); analogwrite(pwmb, 255);

18 79. What is displayed? int w = fx( 28 ); Serial.println( w ); w = fx( 8 ); Serial.println( w ); int fx( int a ){ if ( a > 20 && a < 40 ) return 1; if ( a >= 0 && a <= 30 ) return 2; if ( a >= 0 ) return 3; return 4; 80. What is displayed after the loop function has been executed twice? int x = 30; x = fly( x, 3 ); Serial.println( x ); int fly( int a, int b ){ return a + b; Unit 6 Review. 81. If x has a value of 511, what is the value of y? int x = analogread( A5 ); int y = map( x, 0, 1023, 20, 160 ); 82. What are the possible values of b? a) Any number from 200 to 300. b) Either 200 or 300. c) Always 200. d) Always 300. int a = digitalread( 8 ); int b = map( a, 0, 1, 200, 300 ); I will not ask you any questions about servos or sound detectors.